Phase composition, transition and structure stability of functionally graded cemented carbide with dual phase structure

作     者：张立 陈述 熊湘君 贺跃辉 黄伯云 张传福 

作者机构：State Key Laboratory of Powder Metallurgy Central South University Changsha Mining and Metallurgy Research Institute School of Metallurgical Science and Engineering Central South University 

出 版 物：《Journal of Central South University of Technology》 (中南工业大学学报（英文版）)

年 卷 期：2007年第14卷第2期

页      面：149-152页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学] 070301[理学-无机化学] 

基　　金：Projects(50323008, 50574104) supported by the National Natural Science Foundation of China Project (04JJ3084) supported by the Natural Science Foundation of Hunan Province, China 

主　　题：cemented carbide dual phase structure functionally graded material phase identification fracture toughness testing 

摘      要：The phase composition, phase transition and phase structure transformation of the wire-cut section of functionally graded WC-Co cemented carbide with dual phase structure were investigated by XRD phase analysis. It is shown that the composition of η phase in the core zone is Co_3W_3C (M_6 C type). The structure of cobalt based solid solution binder phase is fcc type. At the cooling stage of the sintering process, the phase transition of η phase, i.e. M_6C→M_12C and the martensitic phase transition of the cobalt based solid solution binder phase, i.e. fcc→hcp are suppressed, which facilitates the strengthening of the alloy. Because the instantaneous temperature of the discharge channel is as high as 10 000 ℃ during the wire cutting process, the processed surface is oxidized. Nevertheless, the oxide layer thickness is in micro grade. In the oxide film, η phase is decomposed into W_2C and CoO, and cobalt based solid solution binder is selectively oxidized, while WC remains stable due to the existence of carbon containing liquid organic cutting medium.