不同工艺参数对离心铸造Al­9Ni­15Si复合材料组织与性能的影响

摘要

采用离心铸造方法在不同工艺条件下制备 Al­9Ni­15Si 复合材料筒状零件，研究不同工艺成形铸件沿径向方向和垂直于轴向方向的微观组织特征，测试不同工艺成形铸件的硬度及耐磨性能。结果表明：Al­9Ni­15Si复合材料铸件形成了外层聚集了大量自生初生Al3Ni/Si颗粒、内层含有较多的初生Si/Al3Ni颗粒以及中间层不含颗粒的3层组织。随着浇注温度和模具温度的升高，铸件外、内层颗粒的体积分数逐渐增加，其硬度值逐渐增大，而体积磨损量逐渐减少。在离心场中，Al3Ni的离心运动和Si的向心漂移是形成Al­9Ni­15Si复合材料3层组织的主要原因；而浇注温度和模具温度越高，合金的凝固时间越长，越有利于形成高体积分数的颗粒偏聚区，从而提高复合材料的力学性能。%The Al­9Ni­15Si composite tubes were prepared under different conditions by centrifugal casting. Along the radial direction and the direction perpendicular to the axial direction of the castings, the microstructure characteristics were investigated, and their hardness and wear resistance were measured. The results show that Al­9Ni­15Si composite castings form a three­layer microstructure including a large number of in­situ primary Al3Ni/Si particles in the outer layer, many primary Si/Al3Ni particles in the inner layer and few particles in the middle layer. As the pouring and mould temperatures increase, the particle volume fractions of the outer and inner layers gradually increase, the hardness values on those zones increase as well, while the volume frictions of them gradually reduce. In the centrifugal field, the centrifugal movement of Al3Ni and the centripetal drift of Si are the main reasons for the formation of the Al­9Ni­15Si composite with three layers. The higher the pouring and mold temperatures are, the longer the solidification time is, and the more beneficial to the formation of high volume fraction particle area is, thus improving the mechanical properties of the composite.