High temperature friction and wear behavior of tungsten – copper alloys

In this paper, high temperature creep and frictional wear behaviors of WCu pseudo-alloys were investigated using scanning electron microscopy, X-ray diffraction and X-ray fluorescence. Results showed that the Cu binder phase was uniformly distributed around the W skeleton in the WCu alloys. The W80Cu20 alloys exhibited a good creep resistance. The creep life of the WCu alloys was gradually reduced with a decrease in W content of the alloy. Copper tungstate (CuWO4) was formed during the high-temperature friction and wear processes, and was found to be beneficial to improve the wear resistance of the WCu alloys. An increase in the content of Cu was found to be helpful to enhance the cohesiveness of W-Cu phases, improve the deformability of W, restrain the formation of WO3, and promote the formation of CuWO4. In addition, the friction coefficient was decreased with an increase in both the Cu content and applied load. Therefore, W70Cu30 alloys demonstrated a better high temperature wear resistance than W80Cu20 alloys. The worn surface of the WCu alloys exhibited pits, furrow, micro-sized pores, fatigue cracks and wear debris. Wear mechanisms of the WCu alloys were identified to be a combination of adhesive wear, abrasive wear, oxidation wear, fatigue wear and evaporation of copper.