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Squeeze casting process can effectively resolve the casting difficulties for wrought aluminum alloys by pressurized solidification. The effects of applied pressure (0.1–125 MPa) on the microstructure refinement, non-equilibrium eutectic phase aggregation and fracture behavior of Al-Zn-Mg-Cu alloys prepared by squeeze casting were investigated through metallography, scanning electron microscopy and energy dispersive spectroscopy. The results showed that the primary α-Al grains transformed from coarse dendrites to refined equiaxed grains with increasing pressure. Considerable primary refinement was achieved at 100 MPa, with a significant decrease by 63% in the average grain size from 273 µm to 101 µm; the non-equilibrium eutectic phases were homogenized and refined, and almost dissolved into the Al matrix after T6 heat treatment. The mechanism of solidification behaviors in pressurized solidification was elucidated. Firstly, the applied pressure increased the thermodynamic driving force to promote primary grain nucleation. Secondly, the solute diffusion and constitutional undercooling at the front of the solid/liquid interface front were inhibited by pressure, and grain growth in a dendritic structure was thus restrained. Thirdly, interdependence theory and thermodynamic calculations were conducted to quantitatively describe the primary grain size changes under pressurized solidification. Lastly, the ternary eutectic reaction L → α-Al + T-Mg (Al, Zn, Cu) 2 + Al 2 Cu and binary eutectic reaction L→ α-Al + Al 7 Cu 2 Fe were suppressed by the reduced solute segregation. Furthermore, when the pressure increased from 0.1 MPa to 125 MPa, the ultimate tensile strength was raised from 428 MPa to 538 MPa, almost approaching that of samples by forging process. The refined eutectic phases decreased stress concentration and improved fracture behaviors. [ABSTRACT FROM AUTHOR]

Abstract The nano-SiC p /A356 Al-matrix composites containing 2 wt.% nano-SiC p were synthesized with solid-liquid mixed casting method. The effects of ultrasonic vibration (UV) treatment and squeeze casting on refinement were studied and the role of nano-SiC p distribution on refinement was focused. Results show that both of the secondary dendritic arm spacing (SDAS) of α-Al grains and the size of eutectic Si phase decrease with the increase of the UV time and the applied pressure of squeeze casting. When UV is applied for 3 min, the SDAS of α-Al in composites is 8.1 μm, which is reduced by 49% than that of A356 matrix alloy. The mean diameter and aspect ratio of eutectic Si phase in composites are 0.92 μm and 2.33, and they are reduced by 42% and 32% respectively than those of A356 matrix alloy. When the applied pressure of squeeze casting is 400 MPa, SDAS of α-Al in composites is 6.9 μm, which is reduced by 55% than that of A356 matrix alloy. Both the processes of UV and squeeze casting can affect the refining effects by regulating the distribution of nano-SiC p. The better the dispersion of nano-SiC p is, the better the refinement of α-Al and eutectic Si phase can be achieved. The mechanical properties of 2 wt.% AMNCs are improved with the increase of UV time and applied pressure, which is consistent with the refinement of the composites' microstructure. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Two-stage super vacuum (19 mbar) assisted high pressure die casting (HPDC) was achieved by evacuating from the die cavity and the shot sleeve simultaneously. The effect of super vacuum assisted HPDC on the repeatability of the tensile properties of Al-Si-Mg-Mn die-cast alloy was investigated in comparison with conventional HPDC. The quantitative Weibull analysis confirmed that super vacuum assisted HPDC improved the repeatability of the tensile properties of the alloy. The data and deviation analysis verified that super vacuum assisted HPDC considerably decreased the fluctuations of the ductility of the alloy by 71% in as-cast state and 84% after solution and ageing treatment. The results also showed that super vacuum assisted HPDC improved the ultimate tensile strength and ductility of the as-cast alloy by 5.6% and 43%, respectively, and increased the ductility of the alloy by 21% after solution and ageing treatment. The significant improvements of ductility and the repeatability of tensile properties were originated from the decrease of porosity volume fraction and porosity size in the alloy processed by super vacuum assisted HPDC. The reduction of defect size can improve the stress distribution and retard the crack initiation in castings. Therefore, the tensile strength and ductility were enhanced in the die-cast alloy processed by super vacuum assisted HPDC. [ABSTRACT FROM AUTHOR]

Abstract In the present work, an ultrasonic assisted squeeze casting method is proposed for processing wrought aluminum alloys. A frame-shaped part was fabricated to verify the feasibility of ultrasonic assisted squeeze casting technology. The results show that a 2024 alloy part with a complex shape and good surface quality can be produced by the proposed ultrasonic assisted squeeze casting method. As the ultrasonic power increasing, the microstructures of the squeeze cast parts were clearly refined, and the coarse polygonal or dendritic structures evolved to fine and equiaxed grains. Mechanical properties, such as strength and plasticity, were also improved significantly as the ultrasonic power increasing. When the ultrasonic power was 1.8 kW, the UTS, YS and elongation to fracture were 372 MPa, 246 MPa and 8.5%, which were improved by 20.8%, 21.2% and 84.8%, respectively, compared to a conventional squeeze cast part. Finally, the effect of ultrasonic vibration on mold-filling and solidification was analyzed. [ABSTRACT FROM AUTHOR]

The effect of pressure and pouring temperature on the microstructure, porosity, hardness and yield stress of AA2024 aluminum alloy during squeeze casting process was investigated. At a constant pouring temperature (700 °C), by increasing the applied pressure up to 140 MPa, the hardness increased from 125 HBN to 152 HBN while the yield stress increased from 235 MPa to 340. Moreover, by increasing the applied pressure (to 140 MPa) and reducing the pouring temperature (at 700 °C), the DAS size and the porosity diameter decreased to 12.5 and 0.25 μm, respectively. Thus, the density increased to 2.75 (g/cm 3 ). At a pressure of 140 MPa and 700 °C, an ultra-fine grain structure with an average grain size of 80 nm was observed. At squeezing pressures greater than 70 MPa, the effect of pouring temperature was less important. [ABSTRACT FROM AUTHOR]

An analytic model is presented for quantitatively investigating the impact of friction between the punch and the shot sleeve on dynamic match status during the injection process of squeeze casting, with the ultimate purpose of optimizing machine design and controlling injection process more accurately. By combining lubrication model and friction experiment, the friction characteristics between the punch and the shot sleeve are investigated in four cases of different clearance values. The lubrication model is validated by comparing the calculated and experimental values of the friction coefficient. The friction model of injection process is then established by means of updating incremental boundary conditions iteratively. The temperature and deformation data are collected from laboratory testing and used to compare with the simulation data obtained from both the general model and the proposed friction model. The simulation data from the friction model is approximately in agreement with the experimental data, better than the general model, implying that the proposed analytics model provides more accurate simulation of the friction coefficients. [ABSTRACT FROM AUTHOR]

The microstructures of A356 alloy parts contained near-round or rosette α-Al grains and eutectics at grain boundaries. Melt processing by vibrating slope could refine grain size and eliminate eutectic phase segregation as well as regional segregation which usually occurred in traditional squeeze casting. Average grain diameter of α-Al grain increased from 44 μm to 64 μm, and grain average roundness decreased firstly from 2.9 to 1.7 then increased to 3.3 with the increase of casting temperature. At casting temperature from 670 °C to 680 °C, crack and cooling shut usually occurred in the products due to poor flow ability of the alloy. When the casting temperature was 690 °C, the alloy had a good filling ability and smooth product with fine near-round or rosette α-Al grains and homogenous eutectics has been obtained. The ultimate tensile strength and elongation of semisolid squeeze casting A356 alloy reached 232 MPa and 7%, which were improved by 12% and 21% respectively as comparing with that of traditional squeeze casting. [ABSTRACT FROM AUTHOR]

The combination of light metals (aluminum, magnesium and titanium) and innovative casting processes provides cost-effective technologies to produce lightweight components and systems for many industrial applications. This article provides a comprehensive and yet critical review of light alloy development for cast components used in lightweight and high-performance structural and propulsion applications. It also summarized some latest process innovations in gravity casting, high pressure die casting, and low pressure casting, to overcome some fundamental issues related to defect formation in casting processes. Emerging casting processes developed in the last twenty years, such as semisolid processing, squeeze casting, ablation casting, bimetallic overcasting, and diffusion solidification processing, are discussed for further development. Recent advances in casting simulation and the concept of Integrated Computational Materials Engineering (ICME) are summarized for casting applications. Finally, future perspectives in light alloy development (including green alloys, high entropy alloys and metal matric composites), process innovations (such as high integrity casting, multi-material manufacturing and additive manufacturing), and ICME development are presented to stimulate further research and sustainable development in this important field of metals processing technology. [ABSTRACT FROM AUTHOR]

A novel method named low frequency electro-magnetic stirring assisted near-liquidus squeeze casting (LFEMS-NSC) was developed for preparing Mg-RE alloy castings. The grain refining effect in commercially pure Mg (CP-Mg), peritectic Mg-Zr alloy and eutectic Mg-Gd alloy were comparatively analyzed among conventional gravity cast, squeeze cast and LFEMS-NSC. The results showed that the LFEMS-NSC exhibited effective grain refining efficiency in CP-Mg and Mg-Gd alloys. With changing conventional gravity casting or squeeze casting to LFEMS-NSC, the grain morphologies of CP-Mg were transformed from coarse columnar into fine equiaxed grains. The average grain size of CP-Mg was refined from ~10 mm to ~232 µm, where the grain refinement efficiency was comparable to that of adding Mg-Zr master alloy. The application of LFEMS-NSC to Mg-Zr and Mg-Gd alloy systems also show considerable grain refining effect, and it show different effectiveness when the solute content varies. The grain refinement mechanism of LFEMS-NSC is mainly because of the enhanced survival rate of free chill crystals and enhanced heterogeneous nucleation rate through melt pre-treatment by LFEMS and applied pressures during solidification. [ABSTRACT FROM AUTHOR]

Abstract: Cooling curves were obtained to estimate solidification parameters of a squeeze cast Al–4%Cu alloy under different processing conditions, while microstructural analysis was carried out to investigate grain morphology obtained for the different test runs. The results indicated not only an increase in cooling curve gradient with increase in pressure, but also a change in cooling curve profile with changes in superheat and die temperature. Solidification range was also affected with an increase in liquidus when superheat was high while solidification rate was decreased when superheat was low and die temperature was increased. Microstructure showed refinement, dendritic growth formation and a suppression of both precipitated phase as well as micro-segregation with an increase in cooling rate due to application of pressure. The investigation is expected to provide important insight into the solidification behavior under pressure of an Al–4%Cu alloy that can be used to evaluate its casting feasibility as well as give basic input information for simulation purposes. [Copyright &y& Elsevier]

Abstract: The semisolid slurry of A356 Al alloy was prepared by indirect ultrasonic vibration (IUV) method and then formed by direct squeeze casting (SC). The effects of squeeze pressure and T6 heat treatment on the microstructure and mechanical properties of rheo-squeeze casting (RSC) A356 Al alloy were investigated. The results indicate that with the increase of squeeze pressure, the average diameter of primary α-Al particles decreased, while the densities and mechanical properties of the samples increased. The effect of T6 heat treatment on the mechanical properties is more significant in RSC samples than in conventional SC samples. The tensile strength and elongation of T6 heat treated RSC samples under 100MPa pressure are 338MPa and 8%, respectively. [Copyright &y& Elsevier]

Abstract: In this work, a different wall-thickness 5-step (with thicknesses as 3, 5, 8, 12, 20mm) casting mold was designed, and squeeze casting of magnesium alloy AM60 was performed under an applied pressure 30, 60 and 90MPa in a hydraulic press. The casting–die interfacial heat transfer coefficients (IHTC) in the 5-step casting were determined based on thermal histories throughout the die and inside the casting which were recorded by fine type-K thermocouples. With measured temperatures, heat flux and IHTCs were evaluated using the polynomial curve fitting method and numerical inverse method. For numerical inverse method, a solution algorithm was developed based on the function specification method to solve the inverse heat conduction equations. The IHTCs curves for five steps versus time were displayed. As the applied pressures increased, the IHTC peak value of each step was increased accordingly. It can be observed that the peak IHTC value decreased as the step became thinner. Furthermore, the accuracy of these curves was analyzed by the direct modeling calculation. The results indicated that heat flux and IHTCs determined by the inverse method were more accurately than those from the extrapolated fitting method. [Copyright &y& Elsevier]

Abstract: Liquid forging is a pressurized solidification process, wherein finished components can be produced in a single process from molten metal to solid, utilizing re-useable die tools. In conventional die casting (gravity and pressure), components with a minimum wall thickness of about 0.6mm can be fabricated. However, parts with section thickness as thin as 0.2mm can be liquid forged using near eutectic Al–Si or Al–Si–Cu alloys. Water based lubricant containing micrographite is effective in releasing the component during ejection. In addition, it aids in shaping the component to required dimensional accuracy. These liquid forged parts are pore free. Thermal analysis of liquid forged 0.8mm plate revealed rapid freezing at the rate of about 700°C/s. During the process, die and punch were maintained at 200–250°C. X-ray residual stress analysis on the surface of the liquid forged plate showed high intensity values for 0.1mm plate. Distribution of eutectic silicon at inter dendritic region is extremely fine to nanoscale level. [Copyright &y& Elsevier]

Abstract: Effects of applied pressure and melt and die temperatures on the microstructure of squeeze cast LM13 alloy were examined. The results showed that application of pressure during solidification decreased the grain size and SDAS of the primary α phase and modified the eutectic silicon particles. With application of an external pressure of about 100MPa, the average SDAS and the average aspect ratio of eutectic silicon particles were reduced from 47μm and 5 to about 34μm and 1.5, respectively. SDAS of the primary α phase and the average aspect ratio of eutectic silicon particles decreased slightly with a drop in the melt or die temperatures, reaching to 32μm and 1.25, respectively, for the best conditions. [Copyright &y& Elsevier]

Diamond/Al composites have been considered as the new generation of thermal management material. The critical challenge is that Al 4 C 3 with deteriorating properties is easily generated at the interface of composites by conventional powder metallurgy and infiltration processes. This paper presents an independently developed liquid-solid separation (LSS) technology for fabricating diamond/Al composites with Cr-coated diamond particles. The key parameters of the LSS process such as the blank heating rate and its heating mode, the squeeze casting temperature and pressure, and pressurization time were optimized. Cr coating of the diamond particles led to improved interface characteristics. The higher thermal conductivity of diamond/Al composite with Cr-coated diamond particles is attributed to the favorable interfacial products of Al 13 Cr 2 and AlCr 2. Thermal conductivity of 40 vol.% Cr-coated diamond particles reinforced diamond /Al composites prepared by LSS with the optimal process was 309.20 W m−1 K−1, 108.06 % higher than that of the composite without the Cr coating. The results showed that relative density is a critical factor in optimizing of the bending strength, compressive strength, and thermal conductivity of the composites. No harmful intermetallic Al 4 C 3 is generated at the interface of the composite. LSS technology is the new low-cost and compact method for the fabrication of diamond/Al composites with high thermal conductivity, which has the prospect of industrial application. [ABSTRACT FROM AUTHOR]

Abstract: The workability of aluminium–SiC and Al2O3-reinforced metal matrix composites (APMMCs) prepared by stir-casting, squeeze-casting and powder metallurgy techniques has been studied by using up-set test. Different parameters of APMMC were considered such as type of Al matrix alloy, type of particulate reinforcement and particulate volume fraction and size. The up-set test was conducted on cylindrical specimens with 8mm diameter and 8mm height, successively as repeated compressions with intermediate heat treatment (IHT). Generally, the workability index (WI) has been positively affected by decreasing particulate size and volume fraction (V f). Stir casting resulted in a slightly better workability than that obtained in case of powder metallurgy, while squeeze casting showed promising behavior in the case of composites with high-particulate V f. The highest workability index (WI), was obtained in case of APMMC with wrought Al matrix and SiC reinforcement. Some rolling experiments were additionally conducted on such composite, where WI estimated was compared to that of the up-set tests. [Copyright &y& Elsevier]

Abstract: Both gravity casting and squeeze casting were carried out previously on an aluminium alloy (LM6) and a zinc alloy (ZA3) with different casting temperatures. Tensile, impact and density measurement were conducted. It was found that generally, samples taken from the bottom of the squeeze casting mould gave higher tensile strength, higher impact strength and higher density values. This study was carried out to determine the effect of solidification time on the mechanical properties of the castings. Two analytical methods were used: a steady-state heat flow model and Garcia''s virtual model. It was found that similar results were obtained with both analytical methods. Casting samples taken from the lower part of the squeeze casting mould were found to have a significantly shorter solidification time. For both types of alloys, it was found that generally the shorter the solidification time of the casting, the higher is its density, impact energy, yield strength and ultimate tensile strength (UTS). This study had therefore contributed to a better understanding of the mechanical properties obtained previously from different casting processes. [Copyright &y& Elsevier]

Abstract: Following the success in squeeze casting aluminum components in the automotive industry, squeeze casting of magnesium alloys is yet to be developed for further improvement on vehicles’ fuel economy. It is essential to have a scientific understanding of solidification phenomena taking place in squeeze casting of magnesium alloys for innovative product development and process control. This paper describes a systematic experimental investigation on solidification phenomena of magnesium alloy AM50A in squeeze casting. The results evidently indicate that an applied pressure leads to an increase in the liquidus temperature of the alloy. However, the pressurized solidification temperatures of AM50A theoretically calculated by the Clausius–Clapeyron equation deviate from the experimental measurements. The measured pressure results imply that local pressures, instead of the hydraulic applied pressures, should be considered during theoretical calculation. [Copyright &y& Elsevier]

Abstract: In squeeze casting process, molten metal is cooled and solidified at a very high level of pressure around and over 40MPa. The time required for solidification is substantially reduced due to enhanced heat transfer at the mould surfaces under high pressure. In the present paper, a fixed grid enthalpy formulation is applied to model solidification for a cylindrical geometry (ϕ 200mm×100mm). The solidification time is estimated at varying heat transfer coefficient with A-356 as the domain material. Higher heat transfer coefficient is interpreted as a consequence of higher applied pressure. The solidification time, as estimated by monitoring liquid fraction, was found to decrease asymptotically with increasing heat transfer coefficient. Segregation pattern in the object was studied by solving the species transport equation. The effect of segregation is found to be negligible for small-volume objects. It is also observed that the contribution of convection can be safely neglected in analysing the solidification process during squeeze casting. [Copyright &y& Elsevier]

Abstract: This paper deals with optimal combination of squeeze cast process parameters, which pose a critical problem to the manufacturing companies. Experiments were conducted by varying squeeze pressure, die pre-heat temperature and pressure duration using L9 (34) orthogonal array of Taguchi method. The mechanical properties such as ultimate tensile strength and hardness of the components have been ascertained and a mathematical model has been developed using multi variable linear regression analysis. The proposed mathematical model is used to formulate the objective functions, which are the pre-requisite of genetic algorithm. The overall objective function is formulated by means of weighted sum approach. Thus, this algorithm is used to search for optimal squeeze cast process parameters to obtain better mechanical properties of the components. [Copyright &y& Elsevier]

Abstract: The ability to produce near net shape components with good surface finish is made possible by means of squeeze casting, a hybrid metal forming process combining features of both casting and forging in a single operation. The primary objective of this paper is to analyze the influence of the process parameters on surface roughness in squeeze casting of LM6 aluminium alloy using Taguchi method. In Taguchi method, a three level orthogonal array has been used to determine the S/N ratio. Analysis of variance and the ‘F’-test values are used to determine the most significant process parameters affecting the surface roughness. The results indicated that the squeeze pressure and the die preheating temperature are the recognized parameters to cause appreciable improvement in the surface finish of the squeeze cast components. [Copyright &y& Elsevier]

Abstract: Hybrid preforms containing SiC whiskers and nanoscale SiC particles were made by wet blending. The Al-based hybrid composites, with 20vol.% SiC whiskers and 0, 2, 5, 7vol.% SiC nanoparticles, were fabricated by squeeze casting route. The optimum squeezing casting parameters, especially infiltration pressure for fabricating the (SiCw·SiCp)/Al hybrid composites were obtained from the infiltration tests. The reinforcements distribute homogeneously in the matrix of the as cast composites, and the strength of the composites is found to increase with increasing content of the nanoparticles. [Copyright &y& Elsevier]

Abstract: Squeeze casting process is the result of search for materials with improved mechanical properties and new casting processes. Desirable features of both casting and forging are combined in this hybrid method. An attempt is made to prepare solid and hollow components of commercially pure bronze, by squeeze casting and to investigate the resulting mechanical properties and grain structure. The components exhibited remarkable grain refinement and substantial improvement in mechanical properties. There is a good scope for processing of such alloys through squeeze casting. [Copyright &y& Elsevier]

Abstract: The paper reports the influence of process variables on a zirconium-free (RZ5DF) magnesium alloy metal matrix composite (MMC) containing 14vol.% Saffil fibres. The squeeze casting process was used to produce the composites and the process variables evaluated were applied pressure, from 0.1MPa to 120MPa, and preform temperature from 250°C to 750°C. The principal findings from this research were that a minimum applied pressure of 60MPa is necessary to eliminate porosity and that applied pressures greater than 100MPa cause fibre clustering and breakage. The optimum applied pressure was established to be 80MPa. It was also established that to ensure successful preform infiltration a preform temperature of 600°C or above was necessary. For the optimum combination of a preform preheat temperature of 600°C and an applied pressure of 80MPa, an UTS of 259MPa was obtained for the composite. This represented an increase of 30% compared to the UTS for the squeeze cast base alloy. [Copyright &y& Elsevier]

This paper deals with the evaluation of the effects of initial stresses developed during the pressurized casting process. The stresses are induced by the external pressure applied to the cast and developed due to thermal loading. The effect of the stresses is considered as a second order effect by means of investigating the influence of the ‘geometric’ or ‘initial stresses’ stiffness matrix on the response of the cast. The problem formulation is done in the updated Lagrangian (UL) frame. An implicit time integration scheme is applied to solve the transient thermomechanical problem in a staggered form. The constitutive mechanical model is elasto-viscoplastic with hardening incorporated with a Mises yield function. The finite element method is employed and a few 3D numerical examples are presented. [Copyright &y& Elsevier]

The paper reports the influence of key process variables on zirconium-free (RZ5DF) and zirconium-containing (RZ5) magnesium–zinc–rare earths alloys by examination of the microstructure and mechanical properties of specimens produced by squeeze casting. Applied pressures from 0.1 to 120 MPa were considered and it was established that an applied pressure greater than 40 MPa was required to suppress the formation of microporosity. Increasing the applied pressure from 0.1 to 60 MPa, produced a reduction in cell size from 127 to 21 μm. The metal pouring and die temperatures considered in the investigation were within the range of 720–780 and 225–275 °C, respectively. It was established that the intermediate die temperature of 250 °C produced the highest tensile properties and that the presence of zirconium did not improve the as-cast properties of the squeeze cast alloy. The highest UTS value obtained for the zirconium-free RZ5DF alloy was 198 MPa compared to 195 MPa for the ZR5 alloy. These UTS value were approximately 50% higher than those for material cast under atmospheric pressure. [Copyright &y& Elsevier]

Gravity casting and squeeze casting were carried out on an aluminium alloy with 13.5% silicon and a zinc alloy with 4.6% aluminium with different temperatures, 660, 690 and 720 °C for the former and 440, 460 and 480 °C for the latter. A top-loading crucible furnace was used to melt the alloys. The die-preheat temperatures used were 200–220 °C for the aluminium alloy and 150–165 °C for the zinc alloy. A K-type thermocouples with digital indicator were used to measure the die surface temperature and the molten metal temperature; while a 25 t hydraulic press with a die-set containing a steel mould was used to perform the squeeze casting with a pressure of 62 MPa. Tensile, impact and density tests were carried out on the specimens. It was found that casting temperature had an effect on the mechanical properties of both gravity cast and squeeze cast aluminium and zinc alloys. The best temperatures to gravity cast the aluminium alloy and the zinc alloy were 720 and 460 °C, respectively. For the squeeze casting of the aluminium alloy, the best temperature to use was either 690 or 660 °C; the former would give a better property at the top of the casting while the latter, at the bottom of the casting. However, for the squeeze casting of the zinc alloy, the best temperature was again 460 °C. [Copyright &y& Elsevier]

Influence of the abnormal structure, such as coarse α phase, scattered chill structure or cold shut, in Japanese Industrial Standard (JIS) AC4CH (Al–7.3%Si–0.3%Mg) aluminum alloy squeeze castings on the reliability of mechanical properties was investigated. The shot time lag (STL) and the heat transfer coefficient between molten alloy and shot sleeve were changed as the process parameters to control the formation of the abnormal structure. Two types of sleeve lubricants, conventional oil-soluble lubricant and new-developed high insulating powder lubricant were used to control the heat transfer coefficient. Both the tensile strength and its reliability were remarkably improved by using the powder lubricant or by decreasing the STL. Regarding the fracture elongation, the average elongation was improved due to the reduction of abnormal structure on the fracture surface. However, the reliability of the fracture elongation was sufficiently improved by neither STL nor the type of lubricants. It is found that the reduction of abnormal structure is effective to improve the strength and fracture elongation of squeeze castings. In order to improve the reliability of these mechanical properties, it will be necessary that the width of the scattering of the abnormal structure size should be decreased. [Copyright &y& Elsevier]

In this work, SiC np /Al6082 aluminum matrix composites were prepared by squeeze casting (SC) combined with stir casting, and the effects of nano-sized SiC particles (SiC np) and SC on microstructure and mechanical properties of the 6082 aluminum alloy were investigated. The result shows that the SiC np were uniformly distributed in the 6082 aluminum matrix alloy using the stir casting. With the addition of the SiC np , the microstructure of the 6082 aluminum alloy was obviously refined, up to 30.55% grain refinement compared to the 6082 aluminum alloy without the addition of the SiC np. The as-cast ultimate tensile strength, yield strength and elongation of the SiC np /Al6082 aluminum matrix composites were enhanced, which increased by 8.92%, 12.16%, and 12.60%, respectively, compared with the 6082 matrix alloy without the SiC np. After the SC, the compactness of the SiC np /Al6082 composites was significantly improved, and the grain of the composites was further refined. The ultimate tensile strength, yield strength and elongation of the SiC np /Al6082 composites fabricated by the SC respectively increased by 29.81%, 43.18%, and 226.28%, compared to the 6082 aluminum alloy obtained by gravity casting (GC). [ABSTRACT FROM AUTHOR]