氧化铪弥散强化钨合金的组织与力学性能研究OA

Hafnium oxide(HfO2)strengthened tungsten(W)alloys with excellent strength and plasticity was prepared by freeze-dr-ying and pressureless sintering.Firstly,uniform W/HfO2 composite nanopowder was in-situ synthesized by the"freeze-drying-hydrogen reduction"process.After being formed by uniaxial pressing at 550 MPa and sintered at 1850℃for 2 hours,W-(0.5%～10%,mass fraction)HfO2 alloys with a density of over 95%was prepared.Unlike the second phase refinement effect of traditional dispersion strengthening materials,the HfO2 particles in W-10%(mass fraction)HfO2 tend to aggregate at the grain boundaries and grow up to 640 nm.The high volume fraction and coarse particle size of the second phase enable the W alloys to achieve the optimal match of strength and plasticity,with a yield strength as high as 2 090 MPa and a fracture strain of 21.0%.Compared with pure W,it has in-creased by 81%and 84%respectively.The in-situ synthesis method of composite powder adopted in this paper provides a way to regu-late the microstructure of the second phase.By regulating the particle size,distribution and volume fraction of the second phase,it is expected to further improve the matching of strength and plasticity of W alloys.