Development and Strength Evaluation of Ultra-fine Grain α-brass for Micromachines

通过反复轧制和热处理，成功获得了平均晶粒尺寸为1.0μm的超细α-黄铜。强度与晶粒尺寸之间存在Hall-Petch关系，超细晶粒材料的强度显著高于常规材料。对市售纯铁细丝进行了拉伸试验和疲劳试验。随着试样直径的减小，屈服现象消失，细丝的疲劳行为与屈服有较强的相关性。对zr基金属玻璃（BMG）进行了疲劳试验，发现BMG板在厚度方向上存在不均匀性，表面强度最高，中部强度最低。BMG的疲劳强度对缺口非常敏感。

Ultra-fine grain α-brass with average grain size of 1.0μm was successfully obtained by repetitive rolling and heat-treatment. Hall-Petch relationships were found between the strengths and the grain size, and then the strengths of the ultra-fine grain material were extremely higher than that of conven-tional materials. Tensile tests and fatigue tests of thin wires of commercially pure iron were conducted. With decreasing the diameter of specimen, the yield phenomenon was disappeared and the fatigue be-havior of the thin wire was strongly dependent on the yielding. Fatigue tests of Zr-based metallic glass (BMG) were also conducted, and found that the BMG plate had inhomogeneity in the thickness direc-tion, where the strength was highest at the surface, and it was lowest in the midsection. The fatigue strength of the BMG was very sensitive to notch.