热处理对W-80Cu板材组织和性能的影响

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

摘要:

本文研究了真空热处理对W-80Cu板材组织演变和性能的影响。采用扫描电镜(SEM)和透射电镜(TEM)观察了W-80Cu板材的微观结构和断口形貌，并对其电导率和力学性能进行了研究。结果表明，热处理后试样的电导率和延伸率均高于未热处理试样，而硬度和抗拉强度均低于未热处理的试样。在600℃下热处理1h，W-80Cu板材的电导率和延伸率最大，韧窝深而密，且分布均匀。W-80Cu板材的室温拉伸断裂方式主要是沿晶断裂和韧窝断裂的混合断裂。当热处理温度在800℃左右及以上，断裂韧窝变得深浅不一，大小也不均匀，局部出现断裂台阶和准解理断裂。当时间超过1h时，出现局部韧窝变大和铜的撕裂脊变长，这与铜晶粒的再结晶长大有关。在热处理过程中W-80Cu板材中的钨相没有明显变化，但试样中钨颗粒周围大量位错及材料中的晶界大大减少。纳米钨颗粒与铜基体之间存在良好的界面关系，这有利于材料强度的提高。

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.