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Studies on the fundamentals of joining dissimilar materials are important given the widespread application of such composite structures in various industries. Titanium (Ti) alloy/stainless steel composites formed by welding are among the most used in this series. Such joints are utilized in the automotive industry, aircraft, power generation, etc. In the joining process, intermetallic TiFe2 and TiFe compounds are formed in the weld seam microstructure and heat-affected zone due to diffusion of Ti and Fe elements. A consequence of this is a significant deterioration of mechanical properties of the joint. Therefore, studies of microstructure and mechanical properties of composites of the Ti–Fe system are relevant and should be performed, especially in terms of microhardness and fracture toughness, to determine the mechanical behavior of various microstructure constituents. Ingots of two chemical compositions (Ti–1.6 wt% Al–39 wt% Fe and Ti–0.6 wt% Al–79 wt% Fe) were produced using an electric arc furnace. They were ground, polished, and etched to be ready for metallographic studies. A Vickers indentation test was carried out using multiple indentations along a line. The microstructure and phase composition analyses of the materials were also performed. It was concluded that the hardness and brittleness of the Ti50Fe50 and, especially, TiFe2 phases caused significant deterioration of the crack growth resistance and strength of the joint. In the Ti–Al–Fe composite containing the α-Fe (about 46 wt%) and TiFe2 (about 54 wt%) phases, a microhardness ratio for the TiFe2 and α-Fe + TiFe2 phases was found as high as 1.96 showing thus a strong dissimilarity effect. In contrast, in the Ti–Al–Fe composite containing the β-Ti (about 39 wt%) and Ti50Fe50 (about 61 wt%) phases, a moderate microhardness ratio of about 0.99 was revealed for the Ti50Fe50 and β-Ti + Ti50Fe50 phases. This evidenced a slight dissimilarity effect in the latter composite. In both cases, the microhardness ratio for different phases introduced in this study is an effective parameter for evaluating the material reliability.

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Various Microstructure Constituents of Ti–Al–Fe Composites Estimated by a Microhardness Test

  • 会议论文

  • 发表日期：

    2026年

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  • V. V. Kulyk,
  • B. D. Vasyliv,
  • Z. A. Duriagina,
  • P. Y. Lyutyy,
  • V. I. Vavrukh,
  • T. M. Kovbasiuk,
  • O. B. Parneta

摘要

Studies on the fundamentals of joining dissimilar materials are important given the widespread application of such composite structures in various industries. Titanium (Ti) alloy/stainless steel composites formed by welding are among the most used in this series. Such joints are utilized in the automotive industry, aircraft, power generation, etc. In the joining process, intermetallic TiFe2 and TiFe compounds are formed in the weld seam microstructure and heat-affected zone due to diffusion of Ti and Fe elements. A consequence of this is a significant deterioration of mechanical properties of the joint. Therefore, studies of microstructure and mechanical properties of composites of the Ti–Fe system are relevant and should be performed, especially in terms of microhardness and fracture toughness, to determine the mechanical behavior of various microstructure constituents. Ingots of two chemical compositions (Ti–1.6 wt% Al–39 wt% Fe and Ti–0.6 wt% Al–79 wt% Fe) were produced using an electric arc furnace. They were ground, polished, and etched to be ready for metallographic studies. A Vickers indentation test was carried out using multiple indentations along a line. The microstructure and phase composition analyses of the materials were also performed. It was concluded that the hardness and brittleness of the Ti50Fe50 and, especially, TiFe2 phases caused significant deterioration of the crack growth resistance and strength of the joint. In the Ti–Al–Fe composite containing the α-Fe (about 46 wt%) and TiFe2 (about 54 wt%) phases, a microhardness ratio for the TiFe2 and α-Fe + TiFe2 phases was found as high as 1.96 showing thus a strong dissimilarity effect. In contrast, in the Ti–Al–Fe composite containing the β-Ti (about 39 wt%) and Ti50Fe50 (about 61 wt%) phases, a moderate microhardness ratio of about 0.99 was revealed for the Ti50Fe50 and β-Ti + Ti50Fe50 phases. This evidenced a slight dissimilarity effect in the latter composite. In both cases, the microhardness ratio for different phases introduced in this study is an effective parameter for evaluating the material reliability.