Ni–xCr粘结剂对Ti(C,N)基金属陶瓷显微组织和力学性能的影响

Effect of Ni–xCr binders on microstructure and mechanical properties of Ti(C,N)-based cermets

摘要:

采用粉末冶金工艺制备了Ni–xCr(wt%,x=0、10、20、30)粘结剂含量为18wt%和38wt%的Ti(C,N)基金属陶瓷,以研究Ni–xCr粘结剂成分及含量对Ti(C,N)基金属陶瓷显微组织和力学性能的影响。除Ni–30Cr粘结剂含量为38wt%的金属陶瓷外,在其它金属陶瓷中仅观察到了Ni基粘结相和Ti基碳氮化物陶瓷晶粒,而未观察到高Mo高Cr白色组织。粘结剂中含Cr时,陶瓷晶粒的黑芯中易出现非常细小的白色颗粒,特别是粘结剂含量为38wt%时,黑芯中通常出现大量的白色颗粒；并且,粘结剂中Cr含量高时,陶瓷晶粒的灰色外环明显变厚。不管粘结剂含量高低,金属陶瓷的硬度随着粘结剂中Cr含量增加而增加,且粘结剂含量为38wt%时增幅更明显。金属陶瓷的横向断裂强度和断裂韧性在粘结剂含量为18wt%时随着粘结剂中Cr含量增加而下降,而在粘结剂含量为38wt%时随着粘结剂中Cr含量增加先增加后下降,以Ni–10Cr作粘结剂时达到峰值。陶瓷晶粒细化致使沿晶断裂几率增加而穿晶断裂几率下降；通过陶瓷晶粒细化、裂纹偏转、裂纹桥联和诱发微裂纹等机制的协同作用,可显著提高Ti(C,N)基金属陶瓷的横向断裂强度和断裂韧性。

Abstract:

Ti(C,N)-based cermets containing 18 wt% and 38 wt% Ni–xCr (wt%, x=0, 10, 20, 30) were prepared by powder metallurgy, in order to study the effect of the composition and content of Ni–xCr binders on microstructure and mechanical properties of Ti(C,N)-based cermets. Ni-based binder phase and Ti-based carbonitride ceramic grains were observed in the other cermets, except that high-Mo and high-Cr white microstructure was also observed in cermet containing 38 wt% Ni–30Cr binder. There were often very fine white speckles in black core of ceramic grains for cermets with Cr-containing binder, especially at 38 wt% binder, and grey outer rim of ceramic grains became thicker when Cr content was high in binders. Regardless of binder content, hardness of cermets increased with increasing Cr content in binders, and the increase in hardness was more obvious at 38 wt% binder. At 18 wt% binder, transverse rupture strength and fracture toughness of cermets decreased with increasing Cr content in binders, however, at 38 wt% binder, they increased and then decreased with increasing Cr content in binders, and reached the peak at Ni–10Cr binder. Ceramic grain refinement led to the increase in the probability of intergranular fracture, and the synergistic effect of ceramic grain refinement, crack deflection, crack bridging, micro-crack toughening, etc., significantly improved transverse rupture strength and fracture toughness of Ti(C,N)-based cermets.