喷射沉积过共晶Al-Si合金的微观组织和抗磨性能

Microstructure and Wear Resistance of Spray-Deposited Hypereutectic Al-Si Alloy

采用扫描电子显微镜和Falex-6型摩擦磨损试验机研究了普通铸造和喷射沉积过共晶Al-Si合金的微观组织和摩擦学性能.显微组织观察和摩擦磨损试验结果表明,喷射沉积能够显著改变过共晶Al-Si合金中初晶Si相的形态和尺寸,细化合金的基体组织;与普通铸造合金相比,沉积态合金具有更好的耐磨性能.

Hypereutectic Al-Si alloys were fabricated by use of the spray-deposition technique and conventional casting process, respectively. The microstructures of the resulting hypereutectic Al-Si alloys were investigated with a scanning electron microscope. The wear-resistance of the Al-Si alloys sliding against AISI-1045 steel was examined on a Falex-6 friction and wear tester in a pin-on-disc contact configuration. The results showed that the spray-deposited hypereutectic Al-Si alloy was composed of α-Al matrix and Si particles uniformly distributed therein, with the shape and size of the primary Si different from that of the conventional as-cast Al-Si hypereutectic alloy. The spray-deposited hypereutectic Al-Si alloy in sliding against AISI-1045 steel counterpart had much better wear resistance than the conventional as cast Al-Si hypereutectic alloy against the same counterpart as well, which was attributed to the different microstructures of the two alloy specimens. Namely, the fine Si particles in the spray-deposited hypereutectic Al-Si alloy were well bonded to the α-Al matrix and were not liable to break and peel off under the shear stress, while the coarse Si particles in the conventional as-cast Al-Si hypereutectic alloy were weakly bonded to the alloy matrix and were liable to peel off in sliding against the steel, owing to the concentrated shear stress at the sharp edges of the Si particles.