Microstructure and Mechanical Properties of Nano-Size Zirconium Carbide Dispersion Strengthened Tungsten Alloys Fabricated by Spark Plasma Sintering Method

W-(0.2,0.5,1.0)wt%ZrC alloys with a relative density above 97.5%were fabricated through the spark plasma sintering(SPS) method.The grain size of W-1.0wt%ZrC is about2.7 μm,smaller than that of pure W and W-(0.2,0.5)wt%ZrC.The results indicated that the W-ZrC alloys exhibit higher hardness at room temperature,higher tensile strength at high temperature,and a lower ductile to brittle transition temperature(DBTT) than pure W.The tensile strength and total elongation of W-0.5wt%ZrC alloy at 700 ℃ is 535 MPa and 24.8%,which are respectively 59%and 114%higher than those of pure W(337 MPa,11.6%).The DBTT of W-(0.2,0.5,1.0)wt%ZrC materials is in the range of 500 ℃-600 ℃,which is about 100 ℃ lower than that of pure W.Based on microstructure analysis,the improved mechanical properties of the W-ZrC alloys were suggested to originate from the enhanced grain boundary cohesion by ZrC capturing the impurity oxygen in tungsten and nano-size ZrC dispersion strengthening.