含铁基粘结剂的WC硬质合金的蠕变变形
Creep deformation of WC hardmetals with iron-based binders
摘要：
铁由于其较低的成本和毒性而成为WC硬质合金中替代钴的候选者。在900-1200 °C下对WC-FeCr硬质合金进行压缩测试。特别注意的是稳态蠕变速率和应力指数（n）在等应力处理。三个制度的应力依赖性进行了观察。WC-Co的两个特征是：中等应力下的幂律蠕变（n~3）和较高应力（通常> 100 MPa）下的晶界滑动（n~1）。还观察到一个未报道的低应力（<10 MPa）区，其指数为n~2。通过结合电子显微镜与X-射线衍射织构测量，低应力制度是由于粘性流动的粘结剂，这是由扩散蠕变容纳在WC骨架。该机理可适用于其它硬质合金。与类似的WC-Co材料相比，WC-FeCr在1000 °C以下显示出改善的抗蠕变性，这可以通过其较低的自扩散性和WC比Co更低的溶解度来解释。然而，在对应于液态共晶形成的温度（~1140 °C）下，其抗蠕变性变得较差。这些结果表明，FeCr可能是一个合适的替代钴的共晶温度不超过。
英文摘要：
Iron is a candidate to replace cobalt in WC hardmetals, due to its lower cost and toxicity. A WC-FeCr hardmetal was compression tested at 900-1200 °C. Particular attention is paid to the steady-state creep rates and stress-exponents (n) during isostress treatments. Three regimes of stress dependence are observed. Two of these were previously reported for WC-Co: power law creep (n~3) at medium stresses; and grain boundary sliding (n~1) at higher stresses, generally >100MPa. A previously unreported low stress (<10MPa) regime with an exponent of n~2 is also observed. By combining electron microscopy with X-ray diffraction texture measurements, the low stress regime is attributed to viscous flow of the binder, which is accommodated by diffusional creep in the WC skeleton. The mechanism may be applicable to other hardmetals. Compared to analogous WC-Co materials, WC-FeCr shows improved creep resistance below 1000 °C, which can be explained by its lower self-diffusivity, and a lower solubility for WC than Co. However, at temperatures corresponding to liquid eutectic formation (~1140 °C), its creep resistance becomes inferior. These results indicate FeCr may be a suitable replacement for Co provided the eutectic temperature is not exceeded.
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