Effect of TiB2 content on the microstructure and mechanical properties of Ti(C,N)–TiB2–FeCoCrNiAl high-entropy alloys composite cermets

摘要

Composite cermets with different mass ratios of Ti (C,N)/TiBsub2/sub and 10 wt % FeCoCrNiAl high-entropy alloys (HEAs) binder were fabricated by mechanical alloying and vacuum hot press sintering. The effect of the TiBsub2/sub content on the microstructure and mechanical properties of the Ti (C,N)–TiBsub2/sub–HEAs cermets was systematically examined and is discussed in detail. The microstructure was analyzed by X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). The results of this study show that a small amount of Fesub2/subB phase was detected in the XRD patterns besides the Ti(C,N) and TiBsub2/sub phase. The TEM observation shows the presence of a HEAs binder phase, which was tightly bound to Ti(C,N) and TiBsub2/sub phases. The grain size of the composite cermets gradually decreased with increasing TiBsub2/sub content increased from 0 to 45 wt %. The relative density of the composite cermets first increased and then decreased with increasing TiBsub2/sub content from 11.25 to 45 wt %. When the TiBsub2/sub content reached 22.5 wt %, the composite cermets exhibited excellent comprehensive performance. The grain size, relative density, and hard phase of the composite cermets were the dominating factors that determined the mechanical properties with increasing TiBsub2/sub content. The relative density, Vickers hardness, bending strength, and fracture toughness of the Ti (C,N)–22.5 wt % TiBsub2/sub–10 wt % HEAs composite cermets reached 98.86 ± 0.20%, 1954.4 ± 20 HVsub10/sub, 727 ± 20 MPa, and 7.9 ± 0.1 MPa msup1/2/sup, respectively.