Effects of Nitrogen Atmosphere on Microstructure and Mechanical Properties of Ti(C0.5N0.5)-based Cermets

• Published in: Journal of Wuhan University of Technology. Materials science edition Vol. 34; no. 2; pp. 259 - 266
• Main Authors: Cao, Qian, Ye, Jinwen, Liu, Ying, Pang, Jia, Qiu, Weibin, Qiu, Yuchong
• Format: Journal Article
• Language: English
• Published: Wuhan Wuhan University of Technology 01.04.2019
• Subjects: Advanced Materials; Chemistry and Materials Science; Materials Science; Ti(C, N); low-pressure sintering; microstructure; nitrogen
• ISSN: 1000-2413; 1993-0437
• DOI: 10.1007/s11595-019-2044-8

The traditional low-pressure sintering was optimized for the preparation of Ti(C 0.5 N 0.5 )-WC-Mo 2 C-TaC-Co-Ni cermets. Nitrogen was introduced into sintering system during different stages and with different pressures. The morphology and mechanical properties of cermets were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and measurements of transverse rupture strength (TRS), Vickers-hardness ( HV ) and fracture toughness ( K IC ). The degree of denitrification is directly related to the amount of η phase. When nitrogen is introduced into the sintering system, the amount of observed η phase decreases. When nitrogen is introduced during solid-state sintering with appropriate pressure, the core-rim structure is well developed. And TRS and hardness get enhanced while toughness tends to be deteriorated with the nitrogen pressure increasing. When nitrogen is introduced after the sintering temperature reaches 1 350 °C or at higher pressures, the volume fraction of η phase increases. Sintered with a nitrogen pressure of 1.0 kPa during 1 200–1 350 °C, the bulk materials possess enhanced mechanical properties, in which the TRS, HV , and K IC are 1 966 MPa, 1 583 MPa, and 9.08 MPa·m 1/2 , respectively.