Effects of Mechanical Ball Milling Time on the Microstructure and Mechanical Properties of Mo 2 NiB 2 -Ni Cermets

• Published in: Materials Vol. 12; no. 12
• Main Authors: Zhang, Lei, Huang, Zhifu, Liu, Yangzhen, Shen, Yupeng, Li, Kemin, Cao, Zhen, Ren, Zijun, Jian, Yongxin
• Format: Journal Article
• Language: English
• Published: Switzerland 14.06.2019
• Subjects: microstructure; ball milling; powder metallurgy; Mo2NiB2-Ni cermets; mechanical properties
• ISSN: 1996-1944; 1996-1944

Mo NiB -Ni cermets have been extensively investigated due to their outstanding properties. However, studies have not systematically examined the effect of the powder milling process on the cermets. In this study, Mo, Ni, and B raw powders were subjected to mechanical ball milling from 1 h to 15 h. XRD patterns of the milled powders confirmed that a new phase was not observed at milling times of 1 h to 15 h. With the increase in the mechanical ball milling time from 1 h to 11 h, raw powders were crushed to small fragments, in addition to a more uniform distribution, and with the increase in the mechanical ball milling time to greater than 11 h, milled powders changed slightly. Mo NiB -Ni cermets were fabricated by reaction boronizing sintering using the milled powders at different ball milling times. The milling time significantly affected the microstructure and mechanical properties of Mo NiB -Ni cermets. Moreover, the Mo NiB cermet powder subjected to a milling time of 11 h exhibited the finest crystal size and the maximum volume fraction of the Mo NiB hard phase. Furthermore, the cermets with a milling time of 11 h exhibited a maximum hardness and bending strength of 87.6 HRA and 1367.3 MPa, respectively.