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Morphology of the subsurface layers of a Ti-Al-Mo-V alloy after carbonitriding

Research paper by I. M. Pohrelyuk, O. I. Yas’kiv, V. M. Fedirko, O. M. Hrypachevs’kyi, R. V. Proskurnyak

Indexed on: 01 Nov '06Published on: 01 Nov '06Published in: Materials Science



Abstract

We study the influence of the composition of saturating medium, temperature, and partial pressure of nitrogen on the morphology of the subsurface hardened layers in a titanium alloy of the Ti-Al-Mo-V system after carbonitriding. It is shown that, after nitriding and carbonitriding, the subsurface layers consist of a zone of intense interaction with interstitial elements (nitrogen and carbon), i.e., the zone of α-solid solution of titanium, a structurally modified transition zone characterized by a more homogeneous distribution of α-and β-titanium, and the matrix. It is shown that the composition of the saturating medium (nitrogen or nitrogen with carbon) is responsible for the phase-structural changes in the subsurface layers and that the technological conditions of saturation (temperature and partial pressure of nitrogen) specify the depth and degree of gas saturation.