The Evolution of Microstructure and Propertiesof W-80Cu Sheets During Heat Treatment

Abstract:

In this study, the effect of vacuum heat-treatment on the micro-structure evolution and properties of W-80Cu sheets was investigated. The micro-structure and fracture?appearance of W-80Cu sheet were observed by scanning electron microscope (SEM) and transmission electron?microscopy (TEM). The electrical conductivity and mechanical properties were investigated. The results indicated that the electrical conductivity and elongation of the?specimen?after?heat-treatment was higher than those of the un-heated while the hardness and room temperature tensile strength was lower. The maximum electrical conductivity and elongation of W-80Cu sheet after ageing at 600℃ for 1h were achieved and the dimples appeared?more deep and compact, and its?size and distribution became uniform. The tensile fracture of W-80Cu sheet was the?main manner?of?the intergranular brittle?fracture with?dimple?fracture. When raising the heat-treatment temperature around and above 800℃, the size and depth of the dimples become?different and ?the local?emergence of the steps and quasi-cleavage appeared. Once the time was above 1h, the local dimples became big and the tearing ridges of copper got longer due to the recrystallization growth of copper grains. During the heat-treatment, tungsten phase in W-80Cu sheet has not an obvious change, but a lot of dislocations around tungsten particles and grain boundary decrease. Both tungsten nano-partials and copper matrix have a good interface relation, which benefits to enhance the strength.

Key words:heat-treatment; microstructure; electrical conductivity; mechanical properties