The Effect of Phase Composition on Microstructure and High-Temperature (700–800 °C) Fracture Toughness of Ti–Fe Composites

会议论文
发表日期：

2024年

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V. V. Kulyk,
B. D. Vasyliv,
P. Y. Lyutyy,
Z. A. Duriagina,
V. V. Vira,
V. I. Vavrukh

摘要

Nowadays, a titanium (Ti) alloy/stainless steel composite formed by welding is being used in power generation, aircraft, the automotive industry, etc. This composite structure exhibits specific advantages of both Ti alloy and stainless steel. However, the broad application of such structures is restricted due to the difficulty of joining these dissimilar materials, as a significant mismatch in melting temperature, thermal conductivity, and thermal expansion coefficient of Ti alloy and stainless steel results in the formation of intermetallic TiFe2 and TiFe compounds in the joining process. These brittle phases cause significant deterioration of the crack growth resistance and strength characteristics of the joint. Therefore, it is reasonable to investigate the mechanical behavior of the model composites containing corresponding phases in terms of their fracture toughness in the temperature range of Ti alloy/stainless steel joints operation. This work is aimed at studying the impact of alloying elements Al and Fe on the phase composition, microstructure, and high-temperature fracture toughness of Ti–Fe composites. Materials of two chemical compositions (Ti–1.6 wt% Al–39 wt% Fe and Ti–0.6 wt% Al–79 wt% Fe marked as composite 1 and composite 2, respectively) were manufactured by melting using an electric arc furnace. Fracture toughness tests of specimens with a sharp edge notch were carried out in a temperature range of 20–800 °C. It was found that composite 1 contained two phases, namely β-Ti (39.12 wt%) and Ti50Fe50 (60.88 wt%). Composite 2 contained α-Fe (45.84 wt%) and TiFe2 (54.16 wt%). Drastic changes in microstructure of composite 2 resulted in a significant drop in its high-temperature fracture toughness. Therefore, Ti–Fe composite containing both the β-Ti and Ti50Fe50 phases can be regarded as promising for applications in high-temperature (700–750 °C) components of state-of-the-art power equipment.