Sintering of light aluminium alloys powder has been investigated as a way to substitute steels in automotive and aerospace industries. Premix Al-5.5Zn-2.5Mg-0.5Cu composite powder called Alumix 431D was analyzed in this research. Sintering was carried out under ultra high purity nitrogen gas and before reaching sintering temperature, green samples were delubricated at 400 ∘ C for 30 min. The powder possesses high sinterability by reaching 96% relative density at 580 ∘ C sintering temperature. Formation of liquid phase seems to support achieving high sintering density. Optimum mechanical properties also were obtained under those conditions. T6 heat treatment was done to improve the mechanical properties by formation of precipitation strengthening, and MgZn 2 appears to be dominant strengthening precipitate. X-ray diffraction, optical microscopy, and SEM-EDS were used to characterize powder, and sintered and heat treated samples.

Premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder was analyzed as matrix in this research. Gas atomized powder Al-9Si with 20% volume fraction of SiC particles was used as reinforcement and added into the alloy with varied concentration. Mix powders were compacted by dual action press with compaction pressure of 700 MPa. High volume fraction of SiC particles gave lower green density due to resistance of SiC particles to plastic deformation during compaction process and resulted voids between particles and this might reduce sinterability of this mix powder. Sintering was carried out under ultra high purity nitrogen gas from 565• -580• C for 1 hour. High content of premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder gave better sintering density and reached up to 98% relative. Void between particles, oxide layer on aluminum powder and lower wettability between matrix and reinforcement particles lead to uncompleted liquid phase sintering, and resulted on lower sintering density and mechanical properties on powder with high content of SiC particles. Mix powder with wt90% of Alumix 431D and wt10% of Al-9Si-vf20SiC powder gave higher tensile strength compare to another mix powder for 270 MPa. From chemical compositions, sintering precipitates might form after sintering such as MgZn 2 , CuAl 2 and Mg 2 Si. X-ray diffraction, DSC-TGA, and SEM were used to characterize these materials.

Lightweight materials of Aluminum-Silicon P/M alloys offer the advantage of high-wear resistance, high strength, good temperature resistance, and a low coefficient of thermal expansion. An A359 MMC alloy was mixed together with Alumix 231 in this research. Powders were compacted with compaction pressure up to 700 MPa. Particle size and compaction pressure influenced green density. Compacted powders were sintered in a tube furnace under a flowing nitrogen gas. Sintering temperature, heating rate and sintering time were verified to determine best sintering conditions of the alloys. Chemical composition also contributed to gain higher sintered density. Precipitation strengthening method was used to improve mechanical properties of this materials.T6 heat treatment was carried out to produce fine precipitates to impede movement of dislocation. The chemical composition of this materials allow for the potential formation of several strengthening precipitates including θ (Al 2 Cu) and β (Mg 2 Si).

In this research, Al-5.5Zn-2.5Mg-0.5Cu was investigated. Compaction pressure at 700 MPa was carried out to make green body materials. Strong interlocking between particles is expected after high compaction process. Sintering of aluminum composites powder is sensitive to the humidity. High purity nitrogen gas was used to sinter this material from 560o-585°C for 1 hour. Sintering density increased with increasing sintering temperature and reached 96% relative sintering density at 580°C. Mechanical properties investigation of this material was done with hardness and tensile test. At optimum sintering conditions, this material has 40 HRB hardness and 329 MPa tensile strength. Based on chemical composition, this material has possibility to improve mechanical properties by T6 heat treatment. Strengthening precipitates such as MgZn2 and CuAl2 were expected as results from T6 heat treatment. Mechanical properties improved with this treatment with reaching 513 MPa of tensile strength. SEM, DSC-TGA and X-Ray Diffraction were used to characterize this material.