Effects of Y2O3 on the microstructure and mechanical properties of spark plasma sintered fine-grained W-Ni-Mn alloy

Fine-grained W-Ni-Mn-Y2O3 alloys were fabricated by mechanical alloying-assisted spark plasma sintering (SPS), and the effects of Y2O3 content on the microstructure and mechanical properties of the alloys were studied. Fine-grained 90W-6Ni-4Mn-Y2O3 alloys with uniform microstructure and excellent properties were prepared by SPS at 1150 degrees C. The addition of trace Y2O3 inhibited the sintering densification process and refined the W grain size. The average W grain size decreased from 5.5 mu m to 2.1 mu m. The fracture mode changed from W grain transgranular fracture and W-W interface fracture to W-W and W-Matrix phase interface fracture. The Rockwell hardness and bending strength of alloys initially increased and then decreased with increasing Y2O3 content. The optimum comprehensive mechanical properties (Rockwell hardness and bending strength) of the alloys were obtained at the same time when the mass fraction of Y2O3 was 0.4%. (C) 2017 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.