炭化タングステンーコバルト系焼結合金の結合相の研究

概要

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In order to clarify the sturctures and the properties of binder phase in cemented tungsten carbide alloy with cobalt, physical properties such as lattice constant, Curie temperature and magnetization of γ-Co solid solution containing up to 15% WC by weight have been studied. Based on these results, the change of the binder phase in WC-5.5% Co composition during the sintering has been first observed. Then, the effect of the various cooling rate from melt on the kinds of alloy phases, and also the structue of γ-Co phase of the Co rich-WC alloys have been investigatd by the method of microscope, X-ray diffraction and thermomagnetic techniques. The results obtained were as follows. By slow cooling, ry or (γ+WC) phases, and by rapid cooling (γ+η) phases appeared on the samples of 5-35% WC-Co alloys. But (γ+η) phases were unstable, and so by annealing, (γ+η) phase changed to stable (γ+WC) phase. These results mentioned above could be described consistently by the double phase diagram containg unstable η phase shown in Fig.8. The process of decomposition of η phase and the simultaneous change of γ phase were also invetigated.
社団法人粉体粉末冶金協会の論文