Affiliation of Author(s):材料科学与技术学院
Journal:JOURNAL OF ALLOYS AND COMPOUNDS
Key Words:Al-Si coating Mechanical alloying Oxidation resistance Multilayered structure
Abstract:An Al-Si coating was successfully fabricated on Ti-6Al-4V alloy substrate by means of mechanical alloying method. The coating was prepared with Al-33.3 wt% Si powder mixture. The coating had a composite structure and its thickness was about 350 mu m. The mass gain and the oxidation rate of the substrate at 850 degrees C were largely decreased because of the as-synthesized coating. The oxidized coating had a multilayered structure, which included an Al diffused layer, a Ti5Si4 interlayer, an inner TiAl3 layer, an outer Ti-Al Si alloy layer and an oxide layer from the inner substrate to the top coating surface. During oxidation, the coating was melted and gradually formed the ternary Ti Al Si alloy with the diffusion of Ti from the substrate to the coating. The Al diffused layer formed with the adequate inter diffusion of the coating and the substrate. The Ti5Si4 interlayer and the inner TiAl3 layer formed owing to their low formation energy at the elevated temperature. The outer Ti Al Si alloy layer mainly included Ti(AlxSi1-x)(2) phase, which formed due to the decrease of Al after the formation of the TiAl3 layer and the oxide layer. The direct oxidation of the outer layer promoted the formation of a continuous oxide layer on the coating surface. These layers could retard and prevent the inward diffusion of oxygen at high temperature. The as-synthesized Al-Si coating could effectively improve the oxidation resistance of the Ti-6Al-4V substrate. (C) 2017 Elsevier B.V. All rights reserved.
ISSN No.:0925-8388
Translation or Not:no
Date of Publication:2017-04-15
Co-author:Chen, Cheng,SHEN Yifu
Correspondence Author:FENG Xiaomei