机械搅拌工艺对Al-25 %Si合金半固态组织演变的影响

Effect of Mechanical Stirring on the Microstructure of Hypereutectic Al-25 %Si Alloy

讨论了冷却至固液两相区内开始搅拌与连续冷却搅拌工艺对半固态Al-25%Si合金组织演变的影响。结果表明,机械搅拌可以破碎在合金液中析出的、生长到一定尺寸的初晶硅;破碎后的初晶硅粒子仍可以发生聚集现象;从初晶硅析出时开始施加机械搅拌将影响其形核和生长动力学,可使初晶硅各向异性生长受到抑制,且会使初晶硅粒子边角钝化。

Discussed emphatically the effect of two different stirring processes,in half-and-half solid-state Al-25% Si alloy,on the microstructure was investigated.Results showed that the mechanical agitation could broken primary silicon when it precipitated from liquid alloy,and grew into a certain size and after being broken the primary silicon particles still could gathering together;Exerted mechanical agitation as the primary silicon precipitation would affect its nucleation and growth dynamics,and its anisotropic growth would be restrained,meanwhile,passivation would take place at the edges of Si particles.