Effect of Initial Microstructures on Hot Deformation Behavior and Workability of Ti2AlNb-Based Alloy

Sibing Wang,Debin Shan,Wenchen Xu,Xunmao Zhong,Yingying Zong

doi:10.3390/met8060382

Abstract

In order to study the effect of initial microstructures on the hot deformation behavior and workability of Ti2AlNb alloy, the isothermal compression experiments of as-rolled and solution-treated Ti–19Al–23Nb–0.5Mo alloys were conducted in the temperature range of 900–1100 °C and strain rate range of 0.001–10 s−1. Subsequently, the processing maps of different state materials were established based on dynamic material model (DMM) and Prasad’s instability criterion. The suitable regions for hot working were determined in the processing maps, which was verified through high-temperature tensile test. The results show that although the solution-treatment could be used to improve the ductility of as-rolled Ti2AlNb alloy at room temperature, the as-rolled microstructure exhibited better hot workability at high temperature compared to the solution-treated microstructure.

Highlights

Ti2 AlNb alloys are attractive candidate materials for use in aviation and automobile industries because of its excellent properties, such as high specific strength, good oxidation resistance, and sufficient creep resistance at elevated temperatures [1,2]
Due to the introduction of amounts of lamellar O phase with superior creep resistance, Ti2 AlNb-based alloys can be used in the temperature range of 600–750 ◦ C [3,4]
The white α2 phase particles were dispersedly distributed in the matrix

Summary

Introduction

Ti2 AlNb alloys are attractive candidate materials for use in aviation and automobile industries because of its excellent properties, such as high specific strength, good oxidation resistance, and sufficient creep resistance at elevated temperatures [1,2]. The hexagonal close-packed (hcp) α2 phase (DO19 structure based on Ti3 Al), and body-centered cubic (bcc) phase β (disordered structure) or B2 phase (ordered structure) exist in the Ti2 AlNb alloys. The α2 phase is a brittle phase with high hardness and B2 phase is a plastic phase, which can increase the strength and improve the ductility of Ti2 AlNb alloys, respectively. Muraleedharan et al [6,7] found that when the content of Nb element in the alloy exceeds 20%, the transition temperature of B2/β phase increases sharply. Xue Chen et al [10] quantitatively investigated the coarsening behavior of the lamellar O phase and its effect on the tensile properties of Ti–22Al–25Nb alloy

Methods

Results

Conclusion