Friction and Wear Properties of Ni₃Al-Ni₃V-V₂C-AlCV₂ Composite in Different Atmospheres

With pure nickel, pure aluminum, pure niobium, pure carbon and 18Al-82V intermediate alloy as raw materials, Ni₃Al-Ni₃V-V₂C-AlCV₂ composite was prepared by vacuum melting. The microstructure, hardness,and friction and wear properties and wear mechanism in different atmospheres (air, oxygen and carbon dioxide) of the composite were studied and were compared with those of the Ni₃Al-Ni₃V alloy. The results show that the composite consisted of blocky Ni₃Al phase, network Ni₃Al+Ni₃V matrix phase, and in-situ generated V₂C and AlCV₂ phases. The hardness of the composite (550 HV) was higher than that of Ni₃Al-Ni₃V alloy (509 HV) due to the solid solution strengthening of some carbon and niobium dissolving in the Ni₃Al phase and Ni₃V phase, and the dispersion strengthening of the V₂C phase and AlCV2 phase formed by the other part of carbon and vanadium and aluminum. The average friction coefficient and wear rate of the composite in the air atmosphere were lower than those of Ni₃Al-Ni₃V alloy. The wear rate of the composite in the carbon dioxide atmosphere was the highest, followed by that in the air atmosphere, and in the oxygen atmosphere. The hardnesses of the wear surface of the composite in the air and oxygen atmosphere were similar, which were 706, 711 HV, respectively, and were higher than that in the carbon dioxide atmosphere (670 HV). The main wear mechanism of the composite was oxidative wear in the oxygen atmosphere, oxidative wear and fatigue wear induced by environmental embrittlement in the air atmosphere, and adhesive wear and abrasive wear in carbon dioxide atmosphere.