Cemented tungsten carbides with Co, Ni or Fe binders were studied by transmission electron microscopy. Particular attention was paid to phase and grain boundaries. A striking feature is the high frequency of coherent carbide/binder interfaces with Fe. The Fe rich binder adopts an epitaxy orientation relationship with prismatic facets of WC, with a parametric misfit of about 1.5%. A special orientation relationship with basal facets of WC grains is sometimes observed with Ni binder, as already noticed for Co. It is associated with a parametric misfit of about 15%. Binder segregation in WC grain boundaries was studied taking into account the effect of carbon content in the alloys. Whatever the binder, no influence of the carbon content could be pointed out. The analyses performed in random grain boundaries in WC-Co alloys agree with the literature value of 0.5 monolayer of segregated Co while slightly larger values are obtained for Ni and Fe binder. ∑ = 2 special grain boundaries were studied in WC-Co and WC-Ni alloys and no segregation was detected. The higher grain boundary segregation as well as the occurrence of coherent interfaces should influence the mechanical properties of WC-Fe alloys.

通过透射电子显微镜研究了具有Co，Ni或Fe粘结剂的硬质合金碳化钨。特别注意了相和晶界。一个显着的特征是与铁的粘结碳化物/粘合剂界面的高频性。富铁粘结剂与WC的棱形面具有外延取向关系，参数失配约为1.5％。镍粘合剂有时会观察到与WC晶粒的基面有特殊的取向关系，正如Co所注意到的那样。这与约15％的参数失配有关。考虑到合金中碳含量的影响，研究了WC晶界中的粘结剂偏析。无论使用哪种粘合剂，都无法指出碳含量的影响。在WC-Co合金的随机晶界中进行的分析与偏析Co的0.5单层的文献值一致，而对于Ni和Fe粘合剂则获得了稍大的值。在WC-Co和WC-Ni合金中研究了∑ = 2个特殊的晶界，未发现偏析。较高的晶界偏析以及相干界面的出现应影响WC-Fe合金的力学性能。