The dispersion of WC grains Into the interior of an eutectic liquid has been studied by superimposing the eutectic WC-85wt.%Co liquid on the top surface of presintered WC-l0wt.%Co alloy compacts. The heavy WC grains diffused into the interior of liquid from the WC-l0wt.%Co compacts. According to increasing the treating temperatures and times, the dispersion distance from WC-l0wt.%Co substrates increased. The fine WC grains diffused into the liquid faster than the coarse WC grains. The high microstructural stability of WC-Co alloys having the heavier WC grains dispersed in a lighter Co-rich liquid was attributed to Brownian motion of WC grains in liquid. The motion of WC grains in the liquid appears to be same with the colloid(the disperse phase) in a dispersing medium. The dihedral angle of 0 degree of WC-Co at. toy seems one of key parameters, which enables the WC-Co alloys to have high structural stability without settling the WC grains during liquid phase sintering.

Liquid phase sintering of 90W-6Ni-4Mn alloy has been investigated as functions of sintering atmosphere, heating rate, and reduction temperature. The present work accounts for the thermodynamic oxidatiodreduction reactions of constituent powders of W, Ni and Mn. By discounting these reactions, the previous investigations would obtain only the alloy with large pores and the lowered relative sintered density, by the liquid phase sintering under a dry hydrogen atmosphere. the sintering cycle consisted of a rapid heating to reduction temperatures under high purity nitrogen atmosphere, and holding for 4 hours and sintering at for 1 hour under a dry hydrogen gas. The relative density of the sintered alloy increased with increasing heating rate. As the reduction temperature increased, the relative density increased to the lm theotical density at the duction temture above . The mimsturcatre of sintered alloys has been analysed by a scanning election microscope. The sintered density was compared with those obtained from the other investigators. It was found that the reduction results in the lowered densification of 90W-6Ni-4Mn alloy. This is caused by the fact that reducing reactions of W and Ni oxides contained in W an Ni powders concomitantly leads to oxidizing reaction of Mn powder the oxidized Mn is hardly reduced at sintering temperature and thereby remains large pores in the alloy. It is concluded that the W-Ni-Mn alloy with full density can be obtained by the precise control of atmosphere, heating rate, and sintering temperature.

1μ m이하의 텅스텐 분말에 구리를 균일하게 코팅하는 공정을 새로이 개발했다. 구리가 코팅된 μ m이하의 텅스텐 분말을 이용하여 액상소결하였으며, 구리가 균일하게 분포된 W-Cu합금을 얻을 수있었다. 본 연구에서 개발된 방법에 의해 구리의 함유량을 10wt.%이하로 낮추면서도 균일한 W-Cu합금을 얻을 수 있었으며, 특히 코발트를 같은 방식에 의해 첨가하면 구리액상이 형성된 후 급격히 치밀화하여 96% 이상의 상대밀도를 갖는 W-Cu 합금을 제작하는데 성공하였다. 코발트 첨가에 의한 급격한 치밀화의 증가는 텅스텐과 구리액상 사이의 접착성 향상에 기인하는 것으로 밝혀졌다.