Preparation,physical and mechanical properties of La2O3 second-phase reinforced tungsten alloys
Second-phase reinforced tungsten(W)alloy has excellent properties such as high strength,great creep resistance,and irradiation resistance,it is a highly promising plasma facing material for fusion reactor.In this paper,W-La2O3 composite powders with different La2O3 contents(w(La2O3)=0-1.5%)were prepared by solution combustion synthesis(SCS)using ammonium metatungstate and lanthanum nitrate(La(NO3)3)as the main raw materials.Then the La2O3 second-phase reinforced W alloys were further prepared by spark plasma sintering,and the effects of La2O3 content on the microstructures and mechanical properties of the W alloys were investigated.The results show that W-La2O3 composite powders with average particle size of approximately 200 nm,well dispersion,and uniform distribution of La2O3 can be successfully synthesized using SCS.The addition of appropriate amount of La2O3 can effectively improve the physical and mechanical properties of W alloys.With the increase of La2O3 contents,the microhardness and tensile strength of the La2O3 second-phase reinforced W alloys show a tendency that increases first and then decreases,while the relative density gradually decreases.The microhardness(HV)of W5La alloy reaches the maximum value of 524.10 at w(La2O3)=0.5%.After the addition of the second-phase of La2O3,the fracture mode of the W matrix is changed from W grain fracture predominantly to a mixed fracture with the co-existence of intergranular fracture and transgranular fracture,and the grain size is reduced with an average grain size of 4.1 μm.Compared with pure W,W5La alloy has higher tensile strength and lower ductile-brittle transition temperature(DBTT),and its tensile strength at room temperature and 500℃is 279.6 MPa and 498.9 MPa,respectively,and DBTT is 200-300℃.
NETL
NSTL
万方数据
