The Investigation On The Preparation And Properties Of AlN/Al-Si Composites

The technique of AlN / Al-Si composites fabricated by means of pressing forming and reaction sintering was studied. The reaction mechanism of AlN and the preparation principle of AlN / Al-Si composites was developed. On the base of the study, The preparation process of AlN / Al-Si composites was developed by infiltration of melt technically pure Al into Si3N4 performs and reaction sintering.The phase composition, microstructure, mechanical performance and the interface characteristic were analyzed through the methods such as XRD, SEM, optical microscope, EDS and hardness testing etc. Results showed that the formation mechanism of AlN is a continuous progressive process. The Si atoms replaced separate out from solid phase Si3N4, diffuse and dissolve in liquid phase Al, then form Al-Si alloy solid solution after cooling, commonly distributing around AlN crystal by mode of reticulation. The newer formed AlN behaves finer interface affinity with Al-Si alloy.By the process and structure analysis of AlN / Al-Si composites made by infiltration and reaction sintering, and the test of hardness and bending strength, it was found that the mechanical performance of AlN / Al-Si composites made by the method was relative to reaction sintering degree. If the material had better mechanical performance, it was the base that making Si3N4 react completely.