0.02 mm厚钼箔材的显微组织、织构及性能

Microstructure, Texture and Properties of 0.02mm Molybdenum Foil

摘要:

以粉末冶金烧结坯为原料,通过多道次轧制和中间退火制备了抗拉强度＞795 MPa、延伸率＞1%的0.02 mm厚钼箔。采用场发射扫描电子显微镜、电子背散射衍射以及室温拉伸等手段分析了该箔材的组织、织构及力学性能特征,并与相同工艺下的0.06 mm钼箔进行对比。结果表明：较之于0.06 mm钼箔,0.02 mm钼箔显微组织特征在于晶粒形状皆为颗粒状或细长纤维状,更为均匀细小且长径比更大；其小角度晶界占比降低,尤其是亚晶界的减少更为明显。0.02 mm钼箔中织构组成具有更加向α线织构集中的特点,其晶粒占比达99.7%；虽然两种钼箔的主织构皆为{001}<110>,但变形量更大的0.02 mm的{001}<110>组分占比远低于0.06 mm钼箔,而{112}<110>占比则明显更高。0.02 mm钼箔不同方向的力学性能差距更为突出,用以表征各向异性程度的IPA值在三项力学性能指标上都有不同程度的提升；随着厚度减薄,钼箔不同方向的抗拉强度`R<sub>m</sub>、屈服强度`R_p和延伸率`A<sub>15</sub>、屈强比`R_p/`R_m呈现不同的变化趋势,揭示出RD、TD方向加工硬化,45°-RD方向则形变韧化。

Abstract:

Using powder metallurgy sintered billet as raw material, 0.02 mm molybdenum foil with tensile strength exceeding 795 MPa and elongation exceeding 1% was prepared by multi-pass rolling and intermediate annealing. The microstructure, texture and mechanical properties of the foil were analyzed by means of field emission scanning electron microscopy, electron backscatter diffraction and room temperature tensile test, and were compared with the 0.06 mm one under the same process. The results show that the microstructure characterization of 0.02 mm foil is granular or slender fibrous grain shape, more uniform and finer, and the aspect ratio is larger than 0.06 mm foil. The distribution frequency of low-angle grain boundaries is lower, especially the difference of sub-grain boundaries is more obvious. The texture composition in 0.02 mm molybdenum foil is more concentrated in α-line texture, and its grains account for 99.7%. Although the main texture of two molybdenum foils is {001}<110>, the proportion of {001}<110> component of 0.02 mm foil with larger deformation is much lower than that of 0.06 mm one, while the proportion of {112}<110> is significantly higher. The disparity in mechanical properties of 0.02 mm foil in different directions is more prominent, and the IPA value, which is used to characterize the degree of anisotropy, has been improved to different degrees on three mechanical properties. As the foil is thinned, two different trends which shows in tensile strength, yield strength, elongation and yield ratio of molybdenum foil in different directions reveal work hardening in the RD and TD directions, and deformation toughening in the 45°-RD direction.