중성자 회절법에 의한 Ni-W 합금 소결체의 격자상수 측정

Abstract

Ni-W(1-5 at.%) alloy rods were made by powder metallurgy process including powder mixing, compacting and subsequent sintering. Ni and W powder of appropriate compositions were mixed by a ball milling and isostatically pressed in a rubber mold into a rod. The compacted rods were sintered at <TEX>$1000^{\circ}C-1150^{\circ}C$</TEX> at a reduced atmosphere for densification. The lattice parameters of Ni-W alloys were estimated by a high resolution neutron powder diffractometer. All sintered rods were found to have a face centered cubic structure without any impurity phase, but the diffraction peak locations were linearly shifted with increasing W content. The lattice parameter of a pure Ni rod was <TEX>$3.5238{\AA}$</TEX> which is consistent with the value reported in JCPDS data. The lattice parameter of N-W alloy rods increased by <TEX>$0.004{\AA}$</TEX> for 1 atomic % of W, which indicates the formation of a Ni-W solid solution due to the substitution of nickel atoms by tungsten atoms of larger size.