挤压铸造工艺参数对Al_2O_(3f)/Al-4.5%Cu复合材料凝固方式与组织的影响

Effect of Squeeze Casting Technical Parameters on Microstructure and Solidification Mode of Al_2O_(3f)/Al-4.5%Cu Alloy Composites

挤压铸造制备了Al2O3短纤维/Al 4 5%Cu合金复合材料,研究了关键工艺参数对基体合金凝固方式与组织的影响。结果表明:Al2O3短纤维表面不能作为基体α初晶非自发形核衬底;随凝固冷却速度ε的增大,复合材料基体组织将细化,基体中有更多完整的晶界出现,偏析第二相主要分布于晶界上,其量随ε的增大而明显增多;纤维体积分数Vf的增大将细化基体晶粒尺寸至纤维间隙大小,同时随Vf的增大,主要分布于纤维/基体界面的偏析第二相的量将有所降低;模具、预制块预热温度及合金液浇注温度对复合材料凝固过程的影响归结到对凝固冷却速度的影响上来;外加压力的提高使复合材料基体组织细化。

Al2O3f/Al45%Cu alloy composites are manufactured by squeeze casting. The effect of key technical parameters on the microstructure and solidification mode of composites is researched. The results indicate that the surface of short fiber Al2O3 can not serve as site for heterogeneous nucleation of the α primary dendrite; The matrix grain is fined and more integral crystal boundaries appear in matrix with most second phase around them, as well as the amount of the second phase is increasing with cooling velocity rising; With fiber volume increasing, the matrix grain is fined to average size of fiber interstice, the amount of the second phase which lies mostly around the fiber/matrix interface appreciably reduces as well; The effect of the prefabrication preheated temperature and mound and the alloy pouring temperature on solidification can be supposed to influence the cooling velocity; With the pressure improving, the matrix grain of Al2O3f/Al45%Cu alloy composites can be fined.