HPT不同压力下纯钼组织性能及热稳定性研究

Microstructure and Performance and Thermal Stability of Pure Molybdenum under Different Pressure by HPT

摘要:

通过高压扭转实验,在350℃条件下将难熔金属纯钼粉末制备成相对密度达0.98以上的金属钼坯,利用多种检测手段分析了高压扭转过程中钼粉颗粒孔隙演变及致密强化规律。通过改变预压钼坯压力参数,探讨了压力对压扭钼坯微观结构和力学性能及其热稳定性的影响。结果表明：压力由2.0GPa增大到3.0GPa,压扭钼坯致密度提升显著,其内部亚晶尺寸细化,微观应变增加,试样整体显微硬度值随压力增大而升高,边缘处略有降低。随压力增大,DSC后组织未发生显著长大,热稳定性较好。

Abstract:

The pure molybdenum powder was consolidated to bulk material with the relative density of over 0.98 via high-pressure torsion (HPT) processing at 350 ℃. The deformation of particles and pores, the evolution of crystallite size and dislocation density, and the strengthening mechanism during HPT processing were analyzed through scaning electron microscopy (SEM), X-ray diffraction (XRD) and the Vickers microhardness. The influence of applied pressure during HPT on the microstructure evolution, mechanical properties and thermal stability were discussed. The results show that the relative density and average microhardness of the HPT processed sample were improved obviously with the increasing applied pressure from 2.0 GPa to 3.0 GPa. Also, the crystallite size and microstrain experience a decrease and an increase with the increasing applied preassure which leads to the increase of dislocation density. In addition, the grain size in the HPT processed sample has a finite increase during the DSC processing, which indicates the thermal stability of HPT processed microstructure.