Heat Treatment of WC-Co Hard Metals and Transformation Temperature of Cobalt Binder Phase
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摘要: 本工作證實WC-Co系硬質合金通過熱處理可以提高其抗彎強度。所增加的抗彎強度決定于合金中鈷的含量,鈷含量越高的合金,其抗彎強度的增加重也就越多。主要是由于淬火熱處理抑制了高溫穩定的面心立方鈷相轉變成密排六方鈷相。
本實驗還采用差熱分析儀測定了WC-Co系合金在加熱過程中,密排六方鈷相轉變成面心立方鈷相的相變溫度。發現其相變溫度隨合金中鈷含量的增加而升高,如YG8是742℃,YG15是770℃,YG20是821℃,這是由于高鈷合金的粘結相在升溫過程中有較高的鎢含量。
本實驗中還發現,燒結后低鈷硬質合金要高于高鈷硬質合金的粘結相中的鎢含量,因為低鈷硬質合金的燒結溫度通常是高于高鈷硬質合金,一般說來燒結溫度越高,則粘結相中的鎢含量也就越高,但當燒結態硬質合金再一次加熱時,其鈷結相中的鎢含量要增加。所以淬火后高鈷硬質合金的粘結相中的鎢含量甚至比低鈷硬質合金的粘結相中的還要高,這就是為什么鈷粘結相由密度六方轉變成面心立方的溫度隨硬質合金中鈷含量的增加而提高。Abstract: The present work has found that the transverse rupture strength of WC-Co hard metals can be improved by quenching heat treatment. The icrement of transverse rupture strength(TRS) is dependent on the cobalt content of hard metal.The higher the cobalt content of hard metal is,the more the increament of transverse rupture strength is. The main rea son is that the transformtion of face centered cubic cobalt stable at high temperature to hexagonal closepacked can be depressed by quenchin g heat treatment.The transformation temperature increases with the increase of cobalt content of hard metal by means of differential thermal anaysis because binder phase of high cobalt hard metal contains higher tungsten content than that of low hard metal during reheating.-
Key words:
- cobalt binder phase /
- transformation temperature /
- hard metal
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