Microstructure, Mechanical and Tribological Properties of the Rapidly Solidified NiAI/Cr(Mo,Dy) Hypoeutectic Alloy

摘要

The NiAl/Cr(Mo,Dy) hypoeutectic alloy was fabricated by rapid solidification. The microstructure and mechanical properties as well as tribological properties for the alloy at different temperatures were investigated. The results revealed that the rapidly solidified NiAl/Cr(Mo,Dy) hypoeutectic alloy was composed of primary NiAl, fine NiAl/Cr(Mo) eutectic lamella, NisDy phase and Cr7Ni3 precipitate. The compression test showed that the rapid solidification improved the mechanical properties of the NiAl/Cr(Mo,Dy) hypoeutectic alloy obviously. The dry sliding test results showed that alloy had excellent tribological properties at about 1073 K, which obtained wear rate of 4.9 10~(-14)m~3/m .N and friction coefficient of 0.16 μ. The excellent tribological properties at high temperature may be attributed to the continuous and intact protecting lubricant film which was composed of amorphous, Cr_2O_3 and Al_2O_3 nanoparticles. Between 700 K to 900 K, the alloy demonstrated bad tribological properties, especially the high wear rate, which may be ascribed to the softening of NiAl and Cr(Mo) phases.