Microstructures and properties of ultrafine-grained tungsten produced by equal-channel angular pressing at low temperatures
Microstructures and properties of ultrafine-grained tungsten produced by equal-channel angular pressing at low temperatures
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DOI：
10.1016/j.jnucmat.2012.10.007
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发表时间：
2013-02
影响因子：
3.1
通讯作者：
T. Hao;Z. Fan;S. X. Zhao;G. Luo;C. S. Liu;Fang Qianfeng
中科院分区：
文献类型：
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作者：
T. Hao;Z. Fan;S. X. Zhao;G. Luo;C. S. Liu;Fang Qianfeng
分别在800°C和950°C下采用等通道转角挤压（ECAP）工艺制备了超细晶钨，并通过电子显微镜和维氏显微硬度测试对其进行了表征。随着ECAP挤压道次的增加，W的平均晶粒尺寸逐渐减小，在800°C下挤压2道次后，W的平均晶粒尺寸从初始的6μm左右细化到0.9μm，而在950°C下挤压3道次后，W的平均晶粒尺寸细化到1.5μm。在950°C挤压过程中形成了由刃位错组成的小角度倾斜晶界。800°C挤压后W的断裂失效模式以沿晶断裂为主，950 °C挤压后W的断裂失效模式以穿晶断裂和沿晶断裂共同作用为主。维氏显微硬度从接收态W的约510HV增加到在800°C和950°C下挤出的W的约560HV。而ECAP处理对材料的导热系数影响较小。
The ultrafine-grained tungsten was fabricated by equal-channel angular pressing (ECAP) at 800°C and 950°C, respectively, and was characterized by electron microscopy and Vickers microhardness measurement. The average grain size of W decreases with the increasing number of ECAP extrusion passes and can be refined from the initial value of about 6μm to 0.9μm after two ECAP extrusion passes at 800°C, while it is refined to 1.5μm after three ECAP extrusion passes at 950°C. Small angle tilt grain boundaries consisting of edge dislocations are formed in the 950°C extrusion. Intergranular fracture mode dominates the fracture failure of the W after 800°C extrusion while transgranular facture mode together with intergranular fracture mode play an important role in the fracture failure of the W after 950°C extrusion. The Vickers microhardness increases from about 510HV for the as-received W to about 560HV for the W extruded at both 800°C and 950°C. However, the thermal conductivity was affected only a little by the ECAP processing.