Mechanical Properties and Thermal Stability of W-ZrC/HfC-Re Alloys Fabricated by Spark Plasma Sintering
Four kinds of tungsten-based materials,W-0.5wt％ZrC-(1,3)wt％Re(WZC1R,WZC3R)and W-0.5wt％HfC-(1,3)wt％Re(WHC1R,WHC3R)were prepared by mechanical ball milling and spark plasma sintering(SPS).The microstructures,mechanical properties and thermal stability were investigated.The WZC3R alloy exhibits a high ultimate tensile strength(UTS)of 728 MPa at 500 ℃ and an UTS of 653 MPa at 600 ℃,which are about 2.1 times higher than that of SPSed pure W.The uniformly distributed nano-sized ZrC and HfC particles can pin the grain boundaries and dislocations,thereby increasing the strength and inhibiting grain coarsening.The WHC3R exhibits a total elongation of 13.9％at 400 ℃,and its DBTT is in the range of 300-400 ℃,which is about 200 and 300 ℃ lower than that of SPSed W-ZrC and pure W,respectively.The addition of the solid solution element Re improves the toughness of W materials by increasing the number of available slip planes and reducing the critical stress needed to start plastic deformation.In addition,the four alloys show excellent high-temperature stability with no signifiicant change in grain size and Vickers microhardness even after heat treatments at temperatures reach up to 1600 ℃.The Re element solidly dissolved in W leads to lattice distortion;it can inhibit the diffusion of W atoms at high temperatures,hinder the migration of grain boundary,and slow down the kinetic process of W grain coarsening,thus enhancing the high-temperature stability of the W materials.
NETL
NSTL
万方数据
