Papers by Keyword: Al-Si-Al₂O₃

Abstract: Particles reinforced Al-xwt.%Si-Al₂O₃ (x=10,20) composites are fabricated through in situ reaction sintering of Al and SiO₂ powder by hot isostatic pressing. Outgassing process and the microstructure of composites under different sintering processes are studied.XRD analysis confirms that the best hot outgassing temperature is 500°C,in situ reaction achieves completely and samples A2 and B2 have better microstructure at 550°C then heating-up to 700°C only for 1h.The microstructure analysis indicates that the reinforcement particulates distribute uniformly in the aluminum matrix.The mechanical properties test results show that the tensile strength of A2 is higher than B2. when x=10,the Al-Si-Al₂O₃ composites have better performance.

Abstract: A new approach for the CTE on the basis of Ashelby.s cutting and welding process was made for the analysis of the thermal expansion behaviors of Al-Si alloys and composites. In this theoretical approach, it was considered that relaxation of residual stress could create an elastoplastic zone in the matrix around a particle during cooling. A comparison of the measured CTEs with the calculated ones for the Al-Si-SiC_p and Al-Si-Al₂O₃ composite systems was performed in terms of the volume percent and the size of reinforced phases. The calculated results revealed that the linear CTE of the both composite depends on the size of the reinforce phases, especially at the composite systems with a low volume percent of the reinforce phases. The increase in the volume percentages of Al₂O₃, SiC_p and Si phase lowers the linear CTEs of the systems. The measured CTEs was deviated less than about ten percents from the calculated ones at composites with a high volume percent. The deviations of the CTEs of reinforced phases are about 4 - 6 vol% from real composite systems.