Microstructure, mechanical and wear properties of mechanically alloyed and conventionally sintered Nb-W and Nb-Mo alloys. (2022) - Gardia, D.K.
Highlights: Nb-W and Nb-Mo alloys are fabricated by mechanical alloying and conventional sintering at different compaction pressure. Nb-Mo alloy exhibits higher %relative sintered density compared to Nb-W alloy. Increase in compaction pressure from 375 MPa to 625 MPa increases the hardness for both the alloys. Nb-Mo alloy shows higher wear resistance compared to Nb-W alloy at 500 MPa compaction pressure. Abstract: Nb-W and Nb-Mo exhibit unrestrained solubility in liquid and solid phase, leading to influence the mechanical properties of Nb. In the present work 90Nb-10 W (alloy A) and 90Nb-10Mo (alloy B) (in weight%) are synthesized by mechanical alloying for 10 h and consolidated by conventional pressureless sintering in argon atmosphere at 1450 °C with 2 h of soaking time. The effect of compaction pressure (375 MPa, 500 MPa, 625 MPa) on densification before sintering and densification, hardness after sintering of the alloys is also investigated. Plastic-assisted deformation is more in alloy B against alloy A which enhances the densification during sintering. Elemental mapping and line scanning result of sintered alloy A show the incidence of W in Nb phase, suggesting profound inter-diffusion of W/Nb. Maximum % relative sintered density of 68.89% is achieved in alloy B at 500 MPa pressure. Alloy A exhibits maximum hardness of 3.11 GPa at 625 MPa compared to 2.55 GPa hardness for alloy B compacted at identical compaction pressure. The wear resistance of alloy B is comparatively higher than alloy A, both compacted at 500 MPa pressure.