Effects of aging on microstructure and wear resistance of laser cladding Mo0.5NbTiVCr0.25 high-entropy alloy coating
(1. CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
2. School of Science Materials and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China;
3. Shi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
2. School of Science Materials and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China;
3. Shi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: Refractory Mo0.5NbTiVCr0.25 high-entropy alloy coatings were fabricated on TC4 substrates using laser cladding technology. The coatings were aged at 600, 800 and 1000 °C for 24 h and then water-cooled. The phase composition, microstructure, and mechanical properties of the high-entropy alloy coatings were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), Vickers hardness testing and universal friction wear testing. The results showed that high-entropy alloy coatings retained a body-centered cubic structure after different aging heat treatments. After the aging heat treatment at 800 °C, the coatings exhibited Ti-rich precipitation phases, which were verified as Ti(O,N) face-centered cubic structures by TEM technique. The optimum aging temperature was 600 °C and the hardness of the coating was HV0.2 410. The wear mechanisms of the coatings were adhesive and abrasive wear.
Key words: Mo0.5NbTiVCr0.25 alloy; laser cladding; refractory high-entropy alloy; microstructure; aging; wear