Phase Composition, Nanohardness and Young’s Modulus in Ti-Fe Alloys after Heat Treatment and High Pressure Torsion

Alena S. Gornakova,Elena A. Novikova,Alexander I. Tyurin,Natalia S. Afonikova,Andrey A. Mazilkin,Boris B. Straumal,Mikhail I. Karpov

doi:10.3390/met11101657

Abstract

Four titanium-iron binary alloys were studied. They were preliminarily annealed in the (α + b) and (α + TiFe) regions of the Ti-Fe phase diagram. The changes in the phase composition, nanohardness, and Young’s modulus of the annealed alloys before and after high pressure torsion (HPT) were investigated. Alloys with high iron content after HPT contain a large fraction of the ω phase. The nanohardness of the material in the middle of the radius of the HPT samples varies in the same range of values between 4.4 and 5.8 GPa, regardless of the preliminary annealing. Young’s modulus is a parameter sensitive to structural and phase changes in the material. After HPT, it increases by a factor of 1.5 after preliminary annealing in the (α + b) region in comparison with that in (α + TiFe) region.

Highlights

IntroductionUnlike many of the broadly used alloys (like Cu-, Al-, Mo-, W- or Ta-based ones etc.), titanium has different allotropic modifications at different temperatures and pressures
Titanium alloys are quite attractive for various applications because of their high specific strength, good corrosion resistance and high biocompatibility [1]
The ω-phase can be observed after pressure release in high pressure torsion (HPT)

Summary

Introduction

Unlike many of the broadly used alloys (like Cu-, Al-, Mo-, W- or Ta-based ones etc.), titanium has different allotropic modifications at different temperatures and pressures. From this point of view, it is similar to iron. It gives the opportunity to develop various thermal and mechanical treatments technologies for the titanium-based alloys. The ω-phase can be observed after pressure release It is present as metastable one at ambient temperature and disappears only after a heating up to several hundred degrees centigrade [2,3,7,8,9,10,11,12]. In some Ti-alloys the metastable ω-phase appears even after a certain heat treatment, without application of high pressure [13,14,15,16]

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