Effect of overheating treatment on the wear characteristics of hypereutectic Al-Si alloy

The wear resistance of as-cast hypereutectic Al-Si alloy and 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 morphologies of the worn surfaces and wear debris were examined by scanning electron microscopy. The results show that the wear resistance of hypereutectic Al-Si alloy is increased considerably by overheating treatment. This is especially true when the alloy is subject to relatively high load friction and wear test. The primary silicon in the alloy matrix was broken during the friction, which leaded to the generation of microcracks 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. The finer the primary silicon phase is, the more uniformly the alloy matrix distributes. Subsequently the higher the hardness of the matrix is, the better wear resistance will be.