冷轧对新型Ni-W-Co-Ta高密度合金组织与性能的

在室温环境中对新型Ni-W-Co-Ta高密度合金进行冷轧变形,借助金相显微镜、扫描电镜、透射电镜、X射线衍射仪、背散射电子衍射、电子万能试验机及显微硬度计对新型Ni-W-Co-Ta高密度合金变形过程中的微观组织及力学性能演变规律进行表征。结果表明：随着变形量的增加,新型Ni-W-Co-Ta高密度合金等轴晶粒沿轧制方向不断被拉长,同时产生大量的滑移带协调剧烈的塑性变形,并最终形成纤维组织。变形量的增大导致位错密度急剧增加,位错交互作用显著加强,进而将晶粒尺寸细化至25.5 nm。经过90%的严重塑性变形后,抗拉强度提高到1953 MPa;屈服强度提升至1806 MPa,硬度增加至534 HV,伸长率则急剧下降至9.1%。断口形貌则由韧性断裂向韧性-准解理混合型断裂转变。

Effect of Cold Rolling on Microstructure and Properties of a Novel Ni-W-Co-Ta Heavy Alloy

Novel Ni-W-Co-Ta heavy alloys were cold rolled under room temperatures to characterize the microstructural evolution and mechanical properties by using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, electron back scattered diffraction, tensile testing and microhardness testing. The results show that equiaxial grains were elongated along the rolling direction and a fibrous texture could be observed with an increase in deformation, in which a large number of slip bands were generated to coordinate the intensive plastic deformation. The sharp increase in dislocation density significantly promoted the dislocation interaction, which, in turn, refined the grain size down to 25.2 nm. After 90% severe plastic deformation, the tensile strength is increased to 1953 MPa. The yield strength is increased to 1806 MPa, the hardness is increased to 534 HV, and the elongation is sharply decreased by 9.1%. The fracture morphology changed from a typical ductile fracture to quasi-cleavage and ductile mixed fractures.