碳化钛粒径对碳氮化钛基金属陶瓷微观结构和力学性能的影响

用粉末冶金真空烧结法制备了超细晶粒碳氮化钛Ti(C,N)]基金属陶瓷.研究了原始粉末粒径对Ti(C,N)基金属陶瓷微观结构和力学性能的影响.结果表明:在化学成分相同的条件下,晶粒细化使材料的Vickers硬度和抗弯强度上升,但断裂韧性有所下降.在超细晶粒Ti(C,N)基金属陶瓷微观组织中出现了一种新型的白芯/灰壳结构和一种特殊化合物(Ni2Mo2.5W1.3)Cx.初步研究表明:由于原始粉末粒径微小,促进了扩散反应因而生成了这种芯/壳结构.芯/壳结构有利于提高材料的抗弯强度和断裂韧性.(Ni2Mo2.5W1.3)Cx有利于提高材料的Vickers硬度,但是降低了Ti(C,N)基金属陶瓷的抗弯强度和断裂韧性.

EFFECT OF TITANIUM CARBIDE PARTICLE SIZE ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF TITANIUM CARBONITRIDE BASED CERMETS

Ultra-fine grain Ti(C,N)-based cermets were manufactured by the powder metallurgy vacuum sintering technology.Effect of starting powder size on microstructure and mechanical properties of Ti(C,N)-based cermets were studied.The experimental results indicate that under conditions of the same chemical composition,the Vickers hardness and bending strength of Ti(C,N)-based cermets increase with the decrease of grain size in cermet,while its fracture toughness shows an opposite trend.A new compound that can be denoted as(Ni2Mo2.5W1.3)Cx existed in the microstructure,and a new kind of core/rim structure with a white core and gray rim was also found in the cermets.This new core/rim structure was formed because the reaction diffusion happened easily due to the fine size of the raw powder.It is believed that this new core/rim structure helps to improve the bending strength of the material.The presence of(Ni2Mo2.5W1.3)Cx phase is beneficial to the Vickers hardness,but harmful to the bending strength and fracture toughness of Ti(C,N)-based cermets.