Effect of Lanthanum Oxide Addition on Microstructure and Properties of Molybdenum-Rhenium Alloy
Using powder metallurgy technology,ODS-Mo-14Re was prepared by adding lanthanum oxide to molybdenum-rhenium alloy.The microstructure and mechanical properties at room temperature and high temperature of the molybdenum alloy tubes before and after the addition of lanthanum oxide were analyzed by EBSD,XRD,Vickers hardness tester,and electro-mechanical universal testing machine.The results show that the addition of an appropriate amount of lanthanum oxide can play an effective role in fine grain strengthening and dispersion strengthening of the molybdenum-rhenium alloy.The addition of 0.3％(by mass)lanthanum oxide reduces the average grain size of the molybdenum-rhenium alloy from 22.6 μm to 7 μm.And when lanthanum oxide is added to the molybdenum-rhenium alloy as a fine dispersed second phase,it increases the dislocation density within the grains,causing dislocations to tangle with each other and hindering dislocation movement,thereby improving strength and plasticity of the molybdenum-rheni-um alloy,with a significant dispersion strengthening effect.The tensile strength of Mo-14Re is 725.8 MPa and 195.3 MPa at room temperature and high temperature(1 300 ℃),while that of ODS-Mo-14Re reaches 780.9 MPa and 226.4 MPa,representing increases of 7.6％and 15.9％,respectively,which indicates that the addition of lanthanum oxide significantly improves the mechanical properties at room temperature and high temperature of the molybdenum-rhenium alloy.
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