Study On Microstructure And Sliding Friction And Wear Properties Of Ni₃Al?Cr? Alloy

At present,the application direction of Ni₃Al intermetallic compounds is mainly as a structural member that is resistant to carbon-containing atmosphere and oxidation-resistant atmosphere.Researches were focused on improving room temperature ductility and strengthening and toughening,etc.With the development of research on intermetallic compounds,the study of its tribological property has become very necessary,as long as the material as a part with relative motion involves friction,wear and lubrication problems.This article uses Advanced high-temperature material of Ni₃Al?Cr?alloys as the research object to study the effect of Cr on its microstructure and properties.Study the influence of wear performance on loads and temperature using HT-1000 high temperature friction and wear testing machine.The main findings are as follows:The Cr is dissolved into the Ni₃Al matrix,and there are obvious dendrites in the alloy.With the increasing of Cr content,the hardness of the alloy showed a linear upward trend,and its compressive strength also increased,but the plasticity decreased.In this paper,the wear rate,friction coefficient,wear scar profile,wear scar composition,wear scar morphology,as well as wear debris morphology,cross-sectional morphology and microhardness were described to explain the Ni₃Al?Cr?alloy friction and wear properties at room temperature and high temperature conditions.The wear resistance of Ni₃Al alloy increased with the increase of Cr content at room temperature,and the wear rate increased with the increasing of loads.At high temperature,the wear rate of Ni₃Al?Cr?alloy increased first and then decreased.At 800°C,the wear rate was the lowest,and the adding of Cr content helped to improve the wear resistance of the Ni₃Al alloy,but the wear resistance of Cr was reduced at 600°C.After addition of Cr element,the friction coefficient decreased slightly,and the overall fluctuation trend was not significant.The change of the wear scar curve was consistent with the change trend of the wear rate.The wear mechanism of Ni₃Al?Cr?alloy were abrasive wear and oxidative wear under low load.When the load increased to 10N and 15N,the wear mechanism of Ni₃Al changes to plastic deformation,peeling wear,accompanied by oxidation wear,and Ni₃Al?Cr??X=4,8,12?alloy wear mechanism is still abrasive wear and oxidation wear;Under high load?20N?,The wear mechanism of Ni₃Al and Ni₃Al-4Cr alloy were changed into fatigue wear,severe peeling wear,and oxidation wear.The wear of the Ni₃Al-8Cr was lighter than the first two,while the wear mechanism of the Ni₃Al-12Cr alloy was still abrasive wear and oxidation wear.In the dry friction process,due to the influence of ambient temperature and frictional heat,oxides are easily formed on the surface of the material.The surface of the Cr-added material not only contained NiO+Al₂O₃ oxides with anti-wear effect,but also contained Cr₂O₃ with anti-friction effect.Increasing load was beneficial to the formation of the friction layer.The friction layer with good bonding strength to the substrate had a good protective effect on the substrate hold back the plastic deformation of the substrate.The friction layer thickness was narrow and did not change obviously with the Cr content.The friction layer existed on Ni₃Al?Cr?alloy at high temperature?600°C and 800°C?,which can protect the substrate and reduce the wear rate.In general,the addition of Cr element was beneficial to improve the dry sliding friction and wear properties of the material at room temperature and high temperature.The addition of Cr element at 600°C reduced the wear resistance.