过热处理对Al—Si过共晶合金耐磨性能的影响

考察了过热处理对Ａｌ－Ｓｉ过共晶合金磨损性能的影响。结果表明，过热处理可以改善材料的耐磨性，尤其是高载荷下的耐磨性；并且过热处理温度越高，材料的耐磨性越好。其原因在行组织中的初生硅粒子受粒触应力的作用时，易破碎而形成裂纹和孔洞，从而降低材料的磨损性能。组织中的初生硅越细小且分布越弥散，基体的强度越高，材料的耐磨性越好。

Effect of Overheating Treatment on the Wear Characteristics of Hypereutectic Al-Si Alloy

The wear resistance of as cast hypereutectic Al Si alloy and of the alloys overheated at various temperatures has been investigated with an MM 200 friction and wear tester under dry sliding against AISI 1045 steel. The structure and the morphologies of the worn surfaces and wear debris have been examined by means of scanning electron microscopy (SEM). As the results, the wear resistance of hypereutectic Al Si alloy is increased considerably by overheating treatment. This is especially so when the alloy is subject to relatively high load friction and wear test. SEM observation of the structure and the morphologies of the worn surfaces and wear debris indicates that the primary silicon in the alloy matrix was broken during the friction, which leads to generation of micro cracks and holes near the deformed and non deformed regions of the alloy matrix. This gives rise to the wear rate of the as cast hypereutectic Al Si alloy. Therefore, the finer the primary silicon phase is, the more uniformly the alloy matrix distributes. Subsequently the higher the hardness of the matrix and wear resistance.