In Situ Generated Mg < Sub > 2 < / Sub > 17% Si Particle Reinforced Al - Si Composite Materials Research

Mg2Si/Al-Si composite materials which have good high temperature mechanical properties and wear resistance advantages, because of its simple process, short cycle preparation, the great potential for industrial production and simple material composition, resource-rich, low cost green features, they bring broad prospects for development in industrial sectors. But all kinds of performance are reduced greatly because of the existence of bulky plate shape Mg2Si in the in situ Mg2Si/Al-Si composites.Therefore,Mg2Si/Al-Si comosite materials was prepared by in situ technique on the basis of previous research results,and the effect of different Mg addition amount,casting process parameters,electromagnetic stirring and heat treatment process on the microstructure and mechanical properties of the composites were researched. The major research results of the study are as follows:The effect of casting process parameters on the microstructure and mechanical properties of the Mg2Si/Al-Si composites were obvious. In this study,the best casting process parameters are: the pouring temperature is695℃,cooling in metal mould and quenching in the water. In this condition, the microstructure and mechanical properties of the Mg2Si/Al-Si composites are the best, the particles size of the Mg2Si phase is19.3μm, the shape factor is0.58, the brinell hardness is98.5and the wear loss is4.33×10-4g/m.The effect of different Mg addition amount on the microstructure and mechanical properties of the composites were obvious.In this study,the best Mg addition amount is11%, the particles size of the primary Mg2Si phase is23.4μm, the shape factor is0.49, the brinell hardness is97.5and the wear loss is4.81×10-4g/m.In this study, The best process to treat the Al-Mg2Si-Si composite at different isothermal holding temperature and time in solid-liquid phase region is hold300s at615℃, the particle size of primary Mg2Si is the smallest, the average diameter is20.54μm, and the roundness is the best, the sharp factor is0.67.And the brinell hardness and the wear loss are107.5and2.46×10-4g/m.The microstructure was improved by electromagnetic stirring.In the role of electromagnetic stirring, Mg2Si phase of irregular small block or rose shape were evolved into tiny granular, and these better roundness Mg2Si were even distributed in the matrix.The mechanical properties of the composites which was treated by electromagnetic stirring, were improved obvious compared with the other not, the brinell hardness improved9.6%and the wear resistance improved19%.In this study, the best heat treatment process are:solute at530℃for10h and quench in room temperature water, aging at175℃for8h. After being treated by heat treatment, the hardness of the composites have been increased by18.6%and its wear resistance improved obviously.