In a quest to develop new light metal alloys that can perform excellently at elevated-temperatures (from 300°C to 400°C), a ternary eutectic Al-Cu-Si alloy was exploited to gain a deeper understanding of the alloy system and its suitability for high temperature applications. The alloys studied, with chemical composition of Al-27%Cu-5%Si (by weight percent) with Ni addition in the range of 0 to 1.5%wt, were cast in a rapid solidification casting technique. The solidification characteristics of the alloy was studied using the Thermo-Calc software. Microstructures were characterized in a scanning electron microscope coupled with energy dispersive spectrometry (SEM-EDS). Finally, the elevated-temperatures tensile properties of the alloys were investigated. Comparing the microstructures and mechanical properties of these Al-Cu-Si(-Ni) alloys with conventional Al-Si alloy A319, the refined microstructure with dispersed Ni intermetallic particles formed in the as-cast Al-Cu-Si(-Ni) alloys deliver improved elevated temperature properties. In particular, the yield strength and ultimate tensile strength of the new alloy with 1.5% Ni at 400?C were observed to be 220% and 309% higher, respectively, than for conventional A319 alloy.

The finite element three-dimensional transient model of the annealing process, including conductive and convective heat transfer in an aluminum (Al) coil was developed, implemented, and validated. It combines winding force dependent effective radial thermal conductivity model and the novel convective heat transfer modeling methodology. Experimental validation of the finite element model was performed for two industrial coils having different dimensions, strip thickness and crowning depth. The general agreement between the predicted and measured temperatures for most of the probes was better than 10% at the target material temperature. A series of measurements were configured and performed to supply both the input and validation data for the simulations. The effect of the additional wetted area on the convective heat transfer at the coil base was quantified. The guidelines on the virtual prototyping of the Al coil annealing process were provided, which can be of interest for the process designers.

The effect of fillets formed between the base and plate fins of rheocast aluminium heatsinks on the thermal resistance of the heatsinks has been quantified by simulation. Simulation methodology, including sequential optimization has been developed in order to determine hotspot distributions where the fillets have the maximum effect. Combination of different fillet dimensions with various base thickness levels and aluminium alloys having inhomogeneous thermal conductivity have been investigated. For the studied cases, the effect of fillets on heatsink thermal resistance differs from negligible to 6%. The results would guide thermal designers on contribution of fillets to the heat transfer in multi-fin heatsinks for natural convection.

This paper reports the Laser Aided Additive Manufacturing of nickel-base alloy Nimonic 80A for the purpose of direct building of die inserts for liquid forging. Low porosity level of 0.01-0.04% with reasonable deposition rate was achieved. The micro-hardness showed very good homogeneity. Directionally solidified cellular micro-structure with an average size of 5Όm was observed. Very fine MC-type carbides were detected at the grain boundaries, which function as the strengthening phase of the alloy. © 2009 Elsevier Ltd.

The relationship between microstructure and mechanical properties in cast aluminium alloys is very complex. This relationship is also strongly affected by the casting process and melt handling. In the current study the mechanical properties were investigated and correlated with microstructural features such as porosity, Fe-rich particles, SDAS, Si-length. Process quality measures such as bifilm index, density index, and sludge factor were also investigated. The aim of the work was to understand the critical interactions between material microstructure and process quality in the development of high performance materials.

The effect of Fe-rich particles has been a topic for discussion in the aluminum casting industry because of the negative impact they exert on the mechanical properties. However, there are still contradictions on the effects of various morphologies of Fe-particles. In this study, microstructural characterization of tensile tested samples has been performed to reveal how unmodified and modified Fe-rich particles impact on the tensile behavior. Analysis of additions of Fe modifiers such as Mn and Cr, showed higher amounts of primary Fe-rich particles (sludge) with increased porosity and, as result, degraded tensile properties. From the fracture analysis of tensile tested HIPed samples it could be concluded that the mechanical properties were mainly governed by the Fe-rich particles, which were fracturing through cleavage, not by the porosity.

Castings generally contain pores and defects that can have a detrimental impact on mechanical properties. The hot isostatic pressing (HIP) process is usually applied to reduce internal porosities, which improves the mechanical properties because of the closed porosities. Therefore, this study investigates the effect of the HIP process on the mechanical properties of sand casting A356 aluminum alloys. This investigation was performed in collaboration with Unnaryd Modell, Quintus Technologies, and IAC Ankarsrum. Investigation of the complex interaction between the microstructural features on mechanical properties before and after the HIP process was examined using computed tomography scanning, in-situ cyclic testing, and scanning electron microscope. In the absence of large defects, the fatigue performance was improved. However, a significant variation in the result was found between the different conditions, whereas the coarser microstructure with larger porosities before the HIP process showed decreased ultimate tensile strength and elongation to failure. The samples tested under high cycle fatigue showed a reduced fatigue propagation zone in that the coarser microstructure. Moreover, large cleavage areas containing oxides in the fracture surfaces indicated that the HIP process closes all the porosities, but the oxide films are not creating a strong bonding. Furthermore, the samples tested under low cycle fatigue showed a difference in the crack propagation, whereas the coarser microstructure showed large cracks opened up away from the notch that assists the propagation leading to reduced fatigue life.

This study investigates the effect of hot isostatic pressing (HIPping) on the static and fatigue properties of sand-casting A356 aluminium alloys. HIPping is a method to improve the fatigue properties in aluminium cast material by reducing or eliminating the inner porosities. Investigation of the complex interaction between the microstructural features on mechanical properties before and after the HIPping process was examined using computed tomography and scanning electron microscopy (SEM). Castings generally contain pores and defects that have a detrimental impact on the fatigue properties. The HIPping process closes the porosities in all investigated samples with an increase in density. Without significant defects, the mechanical performance improved in the finer microstructure. However, a considerable variation in the results was found between the different conditions, whereas the coarser microstructure with larger porosities before HIPping showed remarkably reduced results. The high-cycle fatigue-tested samples showed reduced fatigue propagation zone in the coarser microstructure. Moreover, large cleavage areas containing bifilms in the fracture surfaces indicate that the healing process of porosities is inefficient. These porosities are closed but not healed, resulting in a detrimental effect on the static and dynamic properties.

The study aimed to investigate crack initiation and propagation at the micro-scale in heat-treated Al–7Si–Mg cast alloys with different copper (Cu) contents. In-situ cyclic testing in a scanning electron microscope coupled with electron back-scattered diffraction and digital image correlation was used to evaluate the complex interaction between the crack path and the microstructural features. The three-nearest-neighbour distance of secondary particles was a new tool to describe the crack propagation in the alloys. The amount of Cu retained in the α-Al matrix after heat treatment increased with the Cu content in the alloy and enhanced the strength with a slight decrease in elongation. During cyclic testing, the two-dimensional (2D) crack path appeared with a mixed propagation, both trans- and inter-granular, regardless of the Cu content of the alloy. On fracture surfaces, multiple crack initiation points were detected along the thickness of the samples. The debonding of silicon (Si) particles took place during crack propagation in the Cu-free alloy, while cracking of Si particles and intermetallic phases occurred in the alloy with 3.2 wt% Cu. Three-dimensional tomography using focused ion beam revealed that the improved strength of the α-Al matrix changes the number of cracked particles ahead of the propagating crack with Cu concentration above 1.5 wt%.

A new simple approach was developed to assess the Complete Melt Quality of aluminium cast alloys throughout the production line. The approach relies on the concurrent use of reduced pressure tests (RPT) and tensile tests at each station in the production line when the melt is transferred and/or processed. These tests can be used to determine the source of melt-related problems in the production line. Two case studies from the procedure of both an aluminium die-casting and a rheo-casting plant showed that melts were significantly damaged in the tower furnace and got progressively more damaged through the production line proven by the RPT, tensile test, and fracture surface analysis results.

The effectiveness of rotary degassing on the defect formation and mechanical properties of the final casting of aluminium alloy EN AC 46000 was investigated, along with its impact on the energy consumption in the casting furnace. In the melt preparation prior to casting, the molten metal is usually transported from the melting furnace to the casting furnace with rotary degassing as a cleaning procedure. Under the conditions of this specific study, negligible degradation was observed in the mechanical properties of the final cast component in an aluminium EN AC 46000 alloy after removing the rotary degassing step in the process. Furthermore, removing the rotary degassing step led to a reduced temperature drop in the melt, thus minimizing the need for reheating (energy consumption) by up to 75% in the casting furnace. The reduced energy consumption was up to 124,000 kWh in yearly production in a 1500 kg casting furnace. The environmental impact showed a similar to 1500 kg reduction in CO2 for one 1500 kg electrical casting furnace in a year.

This study has aimed to determine the effects of surface quality and pore size, obtained by different levels of hydrogen content of the liquid metal, on the fatigue behavior of an Al–7%Si–3%Cu–Mg casting alloy. Three surface conditions have been studied: as-cast rough, as-cast smooth, and standard machined and polished surface. The S–N curves have shown that surface roughness and hydrogen content individually impact fatigue strength. Surprisingly, the fatigue strength of machined and polished samples, which aligns with standard testing practices, is significantly reduced, compared to other conditions. Fatigue cracks have been observed to initiate at the pores just below the as-cast surface or on the machined surfaces. In all cases, pores have been observed to be surrounded by bifilms. Moreover, hydrogen content and roughness of the as-cast surface have been found to interact to determine the fatigue performance. These findings necessitate a re-evaluation of fatigue testing procedures for cast aluminum components.

This study deals with the microstructural aspects of the deformation behavior in Al-Si-Cu alloy A380. This has been carried out with in-situ tensile testing coupled with EBSD analysis. The alloy specimens having different microstructures with two different secondary dendrite arm spacing (SDAS) of 9 µm and 27 µm were produced by the unique gradient solidification method. The study of misorientation distribution and texture evolution was performed with different tools in EBSD analysis. The texture was not significantly affected by deformation in both types of alloy specimens. With increase in the deformation, the microstructures are characterized by degradation of EBSD patterns and generation of substructures including low angle boundaries (LABs) and high angle boundaries (HABs). In both the microstructures with low and high SDAS, the boundaries were concentrated around eutectic phases; however this behavior was more pronounced at higher SDAS. The increase in the fraction of LABs with deformation was much higher in the microstructure with higher SDAS than with lower SDAS. This localized strain concentration was especially attributed to the large and elongated eutectic Si particles and Fe-rich intermetallics. The lower mechanical properties obtained at higher SDAS are the result of inhomogeneous strain distribution in the microstructure.

Al–Si–Cu alloys were cast with the unique gradient solidification technique to producealloys with two cooling rates corresponding to secondary dendrite arm spacing (SDAS) of ∼9 and ∼27 μm covering the microstructural fineness of common die cast components.The microstructure was studied with optical microscopy and scanning electronmicroscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electronbackscattered diffraction (EBSD). The alloy with higher cooling rate, lower SDAS, hasa more homogeneous microstructure with well distributed network of eutectic and intermetallicphases. The results indicate the presence of Al–Fe–Si phases, Al–Cu phases andeutectic Si particles but their type, distribution and amount varies in the two alloys withdifferent SDAS. EBSD analysis was also performed to study the crystallographic orientationrelationships in the microstructure. One of the major highlights of this study is theunderstanding of the eutectic formation mechanism achieved by studying the orientationrelationships of the aluminum in the eutectic to the surrounding primary aluminumdendrites.

The mechanical properties of Al-Si alloys are affected by several microstructural features such as secondary dendrite arm spacing (SDAS), size and shape of eutectic Si-particles, presence of intermetallics as well as by porosity. In the current study, Al-Si-Cu alloy A380 was prepared by a unique directional solidification method to produce samples with two different SDAS of 9 μm and 27 μm. The lower solidification rate resulted in larger SDAS, larger grain size, larger eutectic Si and larger intermetallics including Fe-rich β phase. The microstructure with higher solidification rate was found to be finer and more homogeneous with smaller eutectic Si and intermetallics. The specimen with larger SDAS exhibited stronger texture than the one with smaller SDAS. The specimen with smaller SDAS showed improved mechanical properties including YS, UTS and ductility. 

During air-slip direct chill casting of aluminum billets, one of the major defects occurring includes traces along the billet called vertical drags (VDs). If the VDs are too deep or too many, then they cause scraping of the billets. As in the subsequent extrusion process, the surface quality is known to impair both the productivity and quality of the profiles. In cast-house practice, many theories circulate about the causes of VD defects and how to avoid them, but in the literature, no thorough treatments have been made to explain this phenomenon. In the current study, the outer appearance, structure around, and compositions at the defects are analyzed. A theory for the formation of the defects, their cause, and how their appearance is coupled to different alloy types is presented. The segregation in the vicinity of the defects is discussed based on deformation of semisolid materials and coupled to Reynolds dilatancy ingranular materials. The theory can explain differences between 6063 and 6005 alloys.

The book looks into the recent advances in the ex-situ production routes and properties of aluminum and magnesium based metal matrix nanocomposites (MMNCs), produced either by liquid or semi-solid state methods. It comprehensively summarizes work done in the last 10 years including the mechanical properties of different matrix/nanoreinforcement systems. The book also addresses future research direction, steps taken and missing developments to achieve the full industrial exploitation of such composites. The content of the book appeals to researchers and industrial practitioners in the area of materials development for metal matrix nanocomposites and its applications.

The high temperature tensile behaviour of the A354 casting aluminum alloy was investigated also evaluating the influence of secondary dendrite arm spacing (SDAS). Cast specimens were produced through a gradient solidification equipment, obtaining two different classes of SDAS, namely 20-25 µm (fine microstructure) and 40-50 µm (coarse microstructure). After hot isostatic pressing and T6 heat treatment, the samples underwent mechanical characterization both at room and high temperature (200 °C). Results of tensile tests and hardness measurements were related to the microstructural features and fractographic characterization, in order to investigate the effect of microstructure and high temperature exposure on the mechanical behaviour of the alloy.

Scientists are required to disseminate the results of research to the society and companies participating in research projects. The dissemination procedure normally consists of seminars, scientific and layman journal contributions, and conferences that generally are not flexible and timely enought to capture industrial needs. In an effort to accelerate knowledge transfer and technology implementation to sustain and improve competitiveness, Jönköping University has developed a one-year online master programme in cast metals and processes in collaboration with the industry. The collaboration includes development of the curriculum, case studies, lectures and study visits. To explore the development process, we performed interviews and a survey with participating students/professionals, teachers and industrial partners. Our results show that a profound two-way knowledge transfer took place, and that course content and teaching were highly relevant to the industry. Furthermore, industry and academia engaged in new joint research collaborations. Consequently, we hypothesize that the procedure for structured knowledge transfer can be implemented in materials education at advanced level to foster engagement between university, industry and society.

A new and unique beta-titanium alloy (Ti. +. 25. mol% (Ta,Nb,V). +. (Zr,Hr,O) has interesting properties such as low elastic modulus, high strength and high elastic deformability as well as Invar and Elinvar properties. These properties have been successfully realized for the round wire or rods by cold working process but not enough for the sheet made by the cold rolling.To improve the mechanical properties of the alloy sheet, the effect of cold severe deformation on the elastic modulus and microstructure of the alloy sheet was experimentally investigated. The samples were processed using the multi directional forging (MDF) and cold plain rolling.The elastic modulus of the alloy sheet which was cold rolled after MDF was lower than that of cold rolled sheet without MDF. The severe cold plastic deformation by MDF was also effective for obtaining isotropic elastic modulus and very fine grain size (∌1ÎŒm) of sheet after plain rolling. The prototype sheet with low elastic modulus (60-65. GPa), high strength (1100. MPa) and high ductility (total elongation more than 10%) was successfully made in the laboratory test by combining MDF and plain rolling at room temperature. © 2009 Elsevier Ltd.

A study was carried out to investigate the crystallographic effects on the performance of cutting poly-crystalline oxygen free copper C10200 (OFC) with single crystalline diamond (SCD) micro-tools. At both large cutting depth and cross-feed rate, as the micro-tool traversed a grain with a crystallographic orientation less favorable for a stable machining process, the work material in front of the rake face was found to be severely deformed. This may lead to a reduced shear angle, thick chip, striation at the back of the chip, high cutting forces, degraded machined surface and the possibility of burr formation. The results showed minimal variations in the machined surface integrity and cutting forces compared to cut amorphous NiP plating with micro-tools. For a high cutting depth, burrs were also observed due to material deformation and pile-up occurring at the groove edges since the localized stress probably built up in front of the rake face. Cutting strategies were demonstrated to improve the performance of cutting OFC with micro-tools and to generate high aspect ratio micro-pillar arrays.

The effect of microstructure on thermal expansion of AZ91D cast alloy was studied. Samples with equiaxed grains and a controlled secondary dendrite arm spacing (SDAS) were fabricated using gradient solidification. SDAS was chosen to represent the range ofmicrostructural scale found in sand castings down to that of high pressure die casting. Optical microscopy and electron backscatter diffraction (EBSD) were used for microstructural characterization. The relation between thermal expansion and microstructuralscale of existing phases precipitated, in particular grain size, SDAS and fraction of Mg17Al12 was analyzed.

In the current study it was observed that the offset yield point of Mg-9%Al-1%Zn alloy was strongly influenced by the connectivity of Mg₁₇Al₁₂. It was suggested that an increase in the fraction of Mg₁₇Al₁₂ from 8% to 11% could lead to the formation of a Mg₁₇Al₁₂ network which resulted in a higher offset yield point. In addition, it was observed that elongation to failure of the Mg-9%Al-1%Zn alloy strongly depended on the fraction of Mg₁₇Al₁₂. Moreover, the apparent toughness showed a strong inverse relation to the secondary dendrite arm spacing. This approach might be extended to forecast the behavior in other magnesium alloys forming a network of the Mg-Al phase.

A high-pressure die-casting process was employed to produce AZ91D components. These cast components were exposed to three different post-treatments: (1) clean blasting, (2) clean blasting and painting, and (3) painting (without clean blasting). The influence of the process parameters first phase injection speed, temperature of fixed half of the die, cooling time, and intensification pressure on distortion and residual stress of the components after each post-treatment were investigated. The results showed that intensification pressure was the most significant factor among the four parameters.

This paper presents a study of distortion and residual stress within a high-pressure die-cast AZ91D component, cast under different processing conditions. The influence of process parameters, i.e., die temperature, cooling time, intensification pressure and first-phase injection speeds, was examined. Distortions were measured using the in-house standard analog quality control fixture. Residual stress depth profiles were measured using a prism hole-drilling method. It was found that the most important process parameter affecting the distortion was intensification pressure and the second most important was temperature difference between the two die halves (fixed and moving side). Tensile residual stresses were found very near the surface. Increasing the intensification pressure resulted in an increased level of tensile residual stresses.

The deformation behavior of AZ91D cast magnesium alloy was investigated using uniaxial tensile tests from room temperature up to 190°C and strain rates from 0.0001 up to 0.1 1/s. In present work gradient solidification in a Bridgeman furnace was employed to study the effect of initial microstructure on the tensile mechanical response of the AZ91D alloy. The furnace drawing rate was varied from minimum 0.3 to maximum 6 mm/s, which yielded a variation of SDAS from 4.2 up to 25 as well as a variation of the fraction of the γ -phase (Mg17Al12),. The effects of microstructural parameters such as SDAS and γ -phase morphology on the yield strength (YS), ultimate tensile strength (UTS) and hardening were investigated

A dislocation density-based constitutive model, including effects of microstructure scale and temperature, was calibrated to predict flow stress of an as-cast AZ91D (Mg-9%Al-1%Zn) alloy. Tensile stress-strain data, for strain rates from 10-4 up to 10-1 s-1 and temperatures from room temperature up to 190 °C were used for model calibration. The used model accounts for the interaction of various microstructure features with dislocations and thereby on the plastic properties. It was shown that the Secondary Dendrite Arm Spacing (SDAS) size was appropriate as an initial characteristic microstructural scale input to the model. However, as strain increased the influence of subcells size and total dislocation density dominated the flow stress. The calibrated temperature-dependent parameters were validated through a correlation between microstructure and the physics of the deforming alloy. The model was validated by comparison with dislocation density obtained by using Electron Backscattered Diffraction (EBSD) technique.

The goal of this book is to present for readers the articles from the 11th International Symposium on the Science and Processing of Cast Iron that was held in September 2017 in Jönköping, Sweden. The content of the book reflects the state of the art, research and development tendencies of cast iron as the main engineering cast material also in the 21st century.

The effect of lanthanum (La)+cerium (Ce) addition on the high-temperature strength of an aluminum (Al)–silicon (Si)–copper (Cu)–magnesium (Mg)–iron (Fe)–manganese (Mn) alloy was investigated. A great number of plate-like intermetallics, Al11 (Ce, La)3-and blocky α-Al15 (Fe, Mn)3Si2-precipitates, were observed. The results showed that the high-temperature mechanical properties depended strongly on the amount and morphology of the intermetallic phases formed. The precipitated tiny Al11 (Ce, La)3 and α-Al15 (Fe, Mn)3Si2 both contributed to the high-temperature mechanical properties, especially at 300◦C and 400◦C. The formation of coarse plate-like Al11 (Ce, La)3, at the highest (Ce-La) additions, reduced the mechanical properties at (≤300) °C and improved the properties at 400 °C. Analysis of the strengthening mechanisms revealed that the load-bearing mechanism was the main contributing mechanism with no contribution from thermal-expansion mismatch effects. Strain hardening had a minor contribution to the tensile strength at high-temperature.

The use of silicon carbide particles (SiCp) as reinforcement in aluminium (Al)-based composites (Al/SiCp) can offer high hardness and high stiffness. The rare-earth elements like lanthanum (La) and cerium (Ce) and transition metals like nickel (Ni) and copper (Cu) were added into the matrix to form intermetallic phases; this is one way to improve the mechanical property of the composite at elevated temperatures. The α-Al15 (Fe,Mn)3 Si2, Al20 (La,Ce)Ti2, and Al11 (La,Ce)3, π-Al8 FeMg3 Si6 phases are formed. Nanoindentation was employed to measure the hardness and elastic modulus of the phases formed in the composite alloys. The rule of mixture was used to predict the modulus of the matrix alloys. The Halpin–Tsai model was applied to calculate the elastic modulus of the particle-reinforced composites. The transition metals (Ni and Cu) and rare-earth elements (La and Ce) determined a 5–15% increase of the elastic modulus of the matrix alloy. The SiC particles increased the elastic modulus of the matrix alloy by 10–15% in composite materials.

Aluminium metal matrix composites were produced by a newly developed stirring device for stir casting with different matrix alloys, SiC particle fractions and sizes to investigate these parameters' influence on the materials' wear performance. The wear performance of the composites was evaluated with dry sliding pin-on-plate tests against a high-speed train brake pad, and the study of wear surfaces was completed by electron microscopy. The formation of an iron-based tribolayer during wear protected the metal matrix composite from further wear damage. The composite reinforced with 19% SiC particles sized 32 μm showed an increasing coefficient of friction during wear, and the wear surface showed traces of third body wear. The rare earth and transition metal added to the matrix alloy increased the hardness of the composite, and the intermetallic phases reduced the development of the Fe-based tribolayer. The composites with small SiC particles presented the Fe transfer on the exposed aluminium surface, with a lower wear rate and friction coefficient than other composites. The direct comparison of composites produced with different sizes of SiC particles highlighted that the relationship between the wear rate and the coefficient of friction of the composites and the brake pad showed a linear trend.

Lightweight SiC-particle-reinforced aluminum composites have the potential to replace cast iron in brake discs, especially for electric vehicles. This study investigates the effect of SiC particle size and matrix alloy composition on the resulting transfer efficiency and particle distribution. The performance of a specially designed stirring head was studied using a water model, and the stirring head conditions were assessed to understand the particle transfer and dispersion mechanisms in the molten aluminum. The standard practice of thermal pre-treatment promotes the wetting of the reinforcing particles and commonly causes clustering before the addition to the melt. This early clustering affects the transfer efficiency and particle dispersion, where their interaction with the melt top-surface oxide skin plays an important role. In addition, the transfer efficiency was linked to the particle size and the chemical composition of the matrix alloy. Smaller particles aggravated the degree of clustering, and the addition of rare earth elements as alloying elements in the matrix alloy affected the particle dispersion. The stirring parameters should be selected to ensure cluster disruption when the carbides are added to the melt.

Road transport and the associated fuel consumption plays a primary role in emissions. Weight reduction is critical to reaching the targeted reduction of 34% in 2025. Weight reduction in moving parts, such as pistons and brake disc rotors, provide a high-impact route to achieve this goal. The current study aims to investigate the formability of Al–Si alloys reinforced with different fractions and different sizes of SiCp to create an efficient and lightweight Al-MMC brake disk. Lanthanum (La) and cerium (Ce) were added to strengthen the aluminium matrix alloy and to improve the capability of the Al-MMC brake discs to withstand elevated temperature conditions, such as more extended braking periods. La and Ce formed intermetallic phases that further strengthened the composite. The analysis showed the processability and thermal stability of the different material’s combinations: increased particle sizes and broader size range mixture supported the formation of the SiCp particle interactions, acting as an internal scaffolding. In conclusion, the additions of Ce and La strengthened the softer matrix regions and resulted in a doubled compression peak strength of the material without affecting the formability, as demonstrated by the processing maps.

Tungsten-nickel-iron heavy metals are fabricated from powders by liquid phase sintering. A study of the sintering mechanism of heavy metals with a low amount of tungsten particles can, depending on sedimentation, only be done under microgravity. At two earlier Texus flights, No 10 & 19, the growth rate and agglomeration of tungsten particles under microgravity were compared to that under gravity and sedimentation. During the first minute sintering period the particles in the agglomerates were separated and the particle distribution became even. The particle growth rate under microgravity, initially high, is slowing down. At further studies under gravity the influence of surface energy between the liquid phase and the tungsten particles have been investigated. Additions of sulphur and cobolt were used to decrease the surface energy and the use of nickel without iron to increase the energy. At a high surface energy the growth rate increases due to increased driving force. Preliminary results from the Texus 26 flight (April 90) are included. © 1991.

The reaction between molten Al and KBF4 and K2TiF6 was analyzed. Additions of the two salts separately, consecutively and simultaneously were made at 800 and 1000 °C. The phases formed were identified and their morphology investigated. When adding K2TiF6 emulsification of the salt occurs. Residual salt containing K, Ti, Al and O was found in addition to slag containing K, Al and O. In an emulsified region, a new globular morphology of Al3Ti-type was found. No evidence of emulsification of KBF4 was found. This implies that the two salts react individually with Al. A new morphology of AlB2, in the form of thin plates, formed presumably at the salt/aluminum interface, was also found.

The microstructure of rheo-cast Mg-Al alloy AM50 produced by the RheoMetal process is investigated and compared with the same alloy produced by conventional high pressure die casting. The size and arrangement of microstructural constituents and pores are characterized quantitatively using image analyzing techniques. The nearest neighbor distribution of the intermetallic particles is determined. The area fraction of porosity in rheo-cast AM50 is about half that found in the high pressure die cast alloy. In rheo-cast material, the distribution of p phase (Mg17Al12) is relatively uniform throughout the cast. In contrast, the beta phase particles tend to form macroscopic agglomerates in high pressure die cast material. The externally solidified grains in the rheo-cast material exhibit a smaller aluminum gradient than in the high pressure die cast alloy. This indicates that the solidification of the rheo-cast material is closer to equilibrium. (C) 2014 Elsevier Inc. All rights reserved.

The corrosion behavior of magnesium-aluminum (Mg-Al) alloy AM50 produced by a rheocasting (RC) technique was examined in the presence and absence of CO2 at three temperatures -4, 4 and 22 degrees C. The slurry preparation in the RC material was performed with the newly developed RheoMetal process. For reference, 99.97% Mg was included in the corrosion exposures. The influence of the microstructure on the atmospheric corrosion of alloy AM50 produced by RC and high pressure die casting (HPDC) was investigated. The RC AM50 alloy showed better corrosion resistance than HPDC AM50 in all the exposure environments studied. For both materials, there was a strong positive correlation between temperature and the atmospheric corrosion rate. The superior atmospheric corrosion behavior of RC AM50 compared to HPDC AM50 is carefully discussed in relation to differences in the as-cast microstructure. This study demonstrates that producing the alloy AM50 by this type of RC technique opens the door to Mg-Al alloys as a promising candidate for various applications where corrosion resistance is of importance.

The capability of the newly developed rheocasting (RC) technique in combination with the RheoMetal process for producing SiC particulate-reinforced AM50 and AZ91D matrix composites (Mg-based MMCs) was investigated. The quality of the MMCs was studied by analyzing the fraction of casting pores, number density of SiC clusters and the uniformity of SiC particles. Solid fraction, particle size and oxidation of SiC particles had strong impacts on the overall quality of the MMCs. The MMCs produced by 40% solid fraction and oxidized micron-sized SiC particles exhibited an excellent casting quality. A low-quality MMC was obtained when non-oxidized sub-micron sized SiC particles were employed. The results showed the formation of various types intermetallic particles and carbides such as MgO, Mg2Si, Al2MgC2, Mg2C3, Al4C3 as the interfacial reaction products of SiC/Mg alloy’s melts. Mg hydride (α-MgH2) was also identified in inter-dendritic regions of the MMCs for the first time.

The atmospheric corrosion behavior of alloy AZ91D produced by a semi-solid metal (SSM) technique and by conventional high pressure die casting (HPDC) was investigated for up to 1176 hours in the laboratory. Alloy AZ91D in the SSM state was fabricated using a rheocasting (RC) technique in which the slurry was prepared by the RheoMetal process. Exposures were performed in 95% RH air at 22 and 4 degrees C. The RC alloy AZ91D exhibited significantly better corrosion resistance than the HPDC material at two temperatures studied. The effect of casting technology on corrosion is explained in terms of the microstructural differences between the materials. For example, the larger number density of cathodic beta phase particles in the HPDC material initially causes relatively rapid corrosion compared to the RC material. During later stages of corrosion, the more network-like beta phase particles in the RC alloy act as a corrosion barrier, further improving the relative corrosion resistance of the RC material.

The corrosion behavior of magnesium-aluminum (Mg-Al) alloy AM50 produced by a rheocasting (RC) technique was examined in the presence and absence of CO2 at three temperatures -4, 4 and 22 degrees C. The slurry preparation in the RC material was performed with the newly developed RheoMetal process. For reference, 99.97% Mg was included in the corrosion exposures. The influence of the microstructure on the atmospheric corrosion of alloy AM50 produced by RC and high pressure die casting (HPDC) was investigated. The RC AM50 alloy showed better corrosion resistance than HPDC AM50 in all the exposure environments studied. For both materials, there was a strong positive correlation between temperature and the atmospheric corrosion rate. The superior atmospheric corrosion behavior of RC AM50 compared to HPDC AM50 is carefully discussed in relation to differences in the as-cast microstructure. This study demonstrates that producing the alloy AM50 by this type of RC technique opens the door to Mg-Al alloys as a promising candidate for various applications where corrosion resistance is of importance.

The phase relations on the B-rich side of stoichiometric TiB2 were experimentally studied. It was found that a peritectic four-phase reaction liquid + AlB12 ⇔ AlB2 + TiB2 occurs at a temperature between 1073 and 1173 K. Part of the Al-rich corner of the Al-Ti-B phase diagram was calculated and isothermal sections at 973, 1073, 1173 and 1273 K are presented. The peritectic four-phase reaction was calculated to occur at 1150 K in agreement with the experimental results. The Al-rich part of the binary Al-B system was reassessed. A eutectic reaction liquid ⇔ AlB2 + (Al) was confirmed to occur at 932.9 K and 0.055 at.% B and a peritectic reaction liquid +AlB12 ⇔ AlB2 concluded to happen at 1150 K (slightly above the four-phase reaction) and 0.60 at.% B, which is at a lower temperature than previously reported.

The divergent reaction between Al and the two salts K2TiF6 and KBF4 are used in the manufacturing of Al-Ti-B master alloys for grain refinement. It is also possible to use the same reaction to make aluminum based metal matrix composites. The formation sequence of TiB2 from the reaction with K2TiF6 and KBF4 is discussed in the view of the formation of a salt/metal emulsion and agglomeration. The highly exothermic reaction with K2TiF6 will aid the formation of an emulsion and Al3Ti form that in a subsequent step transforms into TiB2. It will also support high element transfer efficiency. The reaction with KBF4 causes less heat to evolve and the tendency towards formation of an emulsion and thus lower transfer efficiency resulting in a sluggish formation of AlB2. Simultaneous additions of K2TiF6 and KBF4 increase the transfer efficiency but will cause the formation of stringer defects in a layered structure. © 2005 Elsevier B.V. All rights reserved.