Development of High-strength Porous Metals and Alloys

通过在氢气和氩气或氮气和氩气的混合气体中对熔体进行单向凝固，制备出了长圆柱形孔沿一个方向排列的莲花型多孔金属。孔隙率取决于金属熔体的熔化温度，而孔隙的取向受冻结方向的控制。研究了多孔铜单轴拉伸行为的各向异性。利用多孔铜和多孔铁进行了若干研究。(1)与各种泡沫金属和烧结金属相比，多孔铜的极限抗拉强度和屈服强度表现出优越的力学性能。(2)用扭摆法测量了多孔铜的内摩擦，在673K左右出现了较大的内摩擦峰。这是由于氢对的形成。(3)首次在安全的氮气气氛下成功制备了多孔铁和多孔镍。多孔铁表现出优异的力学性能，这是由于氮的固溶硬化。(4)构建了两种制备多孔金属的设备：(1)容量为500g，容量为7 ~ 10kg。后一种装置使我们能够研究多孔金属的各种应用。

Lotus-type porous metals whose long cylindrical pores are aligned in one direction have been fabricated by unidirectional solidification of the melt in a mixture gas of hydrogen and argon, or nitrogen and argon. The porosity dependes on the melting temperature of the metal melt, while the orientation of the pores is controlled by the freezing direction. The anisotropy in the uniaxial tensile bahaviour of the porous copper is examined. Several investigations have been made using the porous copper and iron.(1) The ultimate tensile strength and the yield strength of the porous copper exhibit superior mechanical properties compared with various foamed metals and sintered metals.(2) Internal friction of the porous copper has been measured by torsion pendulum method, which shows large internal friction peak at about 673K.This is due to hydrogen pair formation.(3) We were succeeded in fabricating porous iron and nickel using safe atmosphere of nitrogen for the first time. The porous iron exhibits superior mechanical property which is due to solid solution hardening of nitrogen.(4) We constructed two apparatuses for fabrication of the porous metals : (1) 500g capacity and 7〜10kg capacity. The latter apparatus enables us to examine various application of the porous metals.