采用半固态挤压铸造方法制备了ZL117合金活塞,研究了活塞不同部位的初生Si的变化。结果表明,初生Si相等效直径由上至下变大,与上部相比,中部、下部分别增加17%和25%;活塞上部初生Si相的固相率比下部显著降低。活塞上部晶粒细化效果最好、Si含量较低,中、下部初生Si较粗大、含量较高。 ZL117 alloy piston was prepared by semi-solid extrusion casting method, and the change of primary Si in different parts of the piston was studied. The results show that the equivalent diameter of primary Si increases from the top to the bottom, and increases 17% and 25% respectively in the middle and the bottom compared with the upper part. The solid fraction of primary Si phase in the upper part of the piston decreases significantly. The upper part of the piston has the best grain refinement effect, the Si content is lower, the middle and lower primary Si are coarse and the content is higher.