Cr_3C_2和VC对Ti(C,N)基金属陶瓷中环形相的价电子结构和性能的影响

EFFECT OF Cr_(3)C_(2) AND VC ON VALENCE ELECTRON-STRUCTURE AND PROPERTIES OF RIM PHASES IN Ti(C,N)-BASED CERMETS

根据固体与分子经验电子理论,计算了Ti(C,N)基金属陶瓷中界面环形相的价电子结构,讨论了其价电子结构与塑性间的关系。当材料晶体结构相同时,Σna可用来比较其塑性的相对高低。Cr在环形相(Ti,Mo)(C,N)中的固溶,可使其塑性增强,V在环形相中的固溶将使其塑性变差。在计算的基础上进行实验,实验结果表明:Cr3C2的适量加入确实有利于提高金属陶瓷的强度,最终所制备出金属陶瓷的强度比典型成分体系材料的提高了1倍以上;尽管VC的加入能使材料的晶粒得到有效地细化,但它使环形相塑性降低,使金属陶瓷的抗弯强度略有增加。

Based on the empirical electron theory (EET) of solids and molecules, the valence-electron structures (VES) of the rim phases in Ti(C,N)-based cermets were calculated, and the relationship between the VES and the plasticity was discussed. The results indicate that the plasticities of materials with the same crystal structure can be compared using the sum of the na values for the covalent bonds. The plasticity of the rim phase (Ti, Mo)(C, N) can be improved by the dissolution of chromium in the rim phase, and also be reduced by the V dissolution in the rim phase. On the basis of the calculated results, a series of experimental results show that adding Cr3C2 to a typical Ti(C, N)-based cermet is advantageous for strengthening the cermet. Consequently the transverse rupture strength of the cermet manufactured with the addition of Cr3C2 is twice as large as that of a typical cermet. However the addition of VC only improves slightly the strength of the cermet because the dissolution of V in the rim phase reduces the plasticity of the rim phase although the VC addition may make the grains much finer.