Ti-6Al-4V 合金の大気酸化挙動に及ぼす微粒子ピーニングの影響

Abstract

The effect of a fine particle peening (FPP) on atmospheric oxidation behavior and tribological properties of Ti-6Al-4V alloy was evaluated. Surface microstructures of oxidized specimens pre-treated with FPP were characterized using scanning electron microscope (SEM), energy dispersive spectrometry (EDS), glow discharge optical emission spectrometry (GDOES) and X-ray diffraction (XRD). The oxide layer formed on the oxidized specimen pre-treated with FPP was thicker than that on the oxidized-only specimen, because the microstructure induced by FPP facilitated the diffusion of oxygen and aluminum elements during the oxidation process. As results of reciprocating sliding wear tests, width of wear track on the oxidized specimen pre-treated with FPP was shallower compared to the oxidized-only specimen. Moreover, the oxide layer formed at the oxidized-only surface was delaminated during tests, otherwise there was no delamination at the oxidized surface pre-treated with FPP. This was because the surface oxide layer exhibited good interface adherence due to the existence of a thick oxygen solid solution layer. These results indicate that the modified layer created by the combination process of FPP and atmospheric oxidation is effective to improve the wear resistance of titanium alloys.