Interactive effects of cyclic oxidation and structural evolution for Ti-6Al-4V/(TiC+TiB) alloy composites at elevated temperatures

JOURNAL OF ALLOYS AND COMPOUNDS

卷:752

Article

Wei, S. L.^1,2  Huang, L. J.¹  Li, X. T.¹  An, Q.¹  Geng, L.¹ 

[1] Harbin Inst Technol, Sch Mat Sci & Engn, Harbin 150001, Heilongjiang, Peoples R China

[2] MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA

关键词: Metal matrix composites;    Powder metallurgy;    Oxidation;    Transmission electron microscopy, TEM;   

DOI  :  10.1016/j.jallcom.2018.04.118

来源: Elsevier

【 摘 要 】

A kind of Ti-6Al-4V alloy matrix composite with coupled (TiC+TiB) networks as reinforcements was conceived and actually prepared by reaction hot pressing technique. Its internal microstructures transferred from Widmanstatten lamellae into equiaxed alpha-Ti grains during in-situ synthesizing reactions, which were characterized by HRTEM analyses to reveal the crystallographic correlations. With an effort to enhance its high-temperature oxidation resistance, the cyclic oxidation kinetics and concomitant structural evolution were experimentally investigated and thermodynamically elucidated in the 873-1073 K temperature range. The specially designed network configuration of hybrid reinforcers was found to improve the oxidation resistance to a remarkable extent. The cyclic oxidation kinetics followed the classic parabolic relation at the relatively lower temperature of 873 K, but this was replaced by a linear trend once temperature rose up to -1073 K. It was revealed that the thermal-stress induced spallation of oxide scales was the dominant factor to modulate the interaction of oxidation kinetics and structural evolution. A phenomenological model of oxide scale growth was proposed accordingly to depict the kinetics transition of cyclic oxidation process. (C) 2018 Elsevier B.V. All rights reserved.

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