Tribological behaviour of AZ71E alloy at high temperatures
(1. Key Laboratory of Manufacture and Test Techniques for Automobile Parts (Ministry of Education),
Chongqing University of Technology, Chongqing 400054, China;
2. School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China)
Chongqing University of Technology, Chongqing 400054, China;
2. School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China)
Abstract: Tribological behaviour of the die-cast AZ71E magnesium alloy was investigated in an applied load range of 10-50 N at high temperatures under dry sliding conditions using a pin-on-disc wear testing machine. The results indicate that the wear rate increases with the increase of applied load and sliding distance, whereas the friction coefficient decreases with the increase of applied load. Scanning electron microscopy and optical microscopy studies on the worn surfaces and sub-surfaces show that the predominant wear mechanism is abrasion at low applied loads. The mild delamination wear accompanying with adhesion wear is the predominant wear mechanism under high applied loads at 150 °C, whereas the severe delamination and melting wear are the predominant wear mechanisms under high applied load at 200 °C. An investigation of the microstructure, thermal stability and tensile properties at high temperatures, using the optical microscopy, X-ray diffraction, differential scanning calorimetry, shows that the dominant secondary phase in AZ71E alloy, Al11Ce3, leads to the improvement in the tensile and elongation properties of alloy at high temperatures, which results in the improvement in the anti wear performance.
Key words: magnesium alloy; dry sliding wear; high temperature wear; wear mechanism