Novel Anisotropic Ductility of a High Strength Annealed Ti-20Zr-6.5Al-4V Alloy.

Bing Zhang,Xing Zhang,Xinyu Zhang,Yuanzhi Jia,Mingzhen Ma,Qin Jing,Riping Liu

doi:10.3390/ma11040529

Abstract

In this work, we investigate the mechanical properties of an annealed high strength Ti-20Zr-6.5Al-4V alloy in uniaxial tensile tests in different directions. The results show that the alloy exhibits obvious anisotropic ductility in different directions, while the tensile strength of the alloy remains almost unchanged. This phenomenon is closely related to α laths with similar orientations along the prior-β grain boundaries. These α laths significantly affect the initiation and propagation of cracks when the alloy reaches its yield limit, thereby affecting the ductility of the alloy, such that it exhibits anisotropic ductility.

Highlights

To identify the microstructure details of the samples, we examined the cross sections perpendicular to the tensile direction using an EDAX-TSL electron backscatter diffraction (EBSD)
The elongation of the samples decreased from 10.8% in A0 to 6.1% in A90
The inverse pole figure (IPF) maps show that in both samples, there are some α laths with similar orientations precipitated along the prior-β grain boundaries

Summary

Introduction

Ti alloys are applied in many fields due to their many excellent properties such as exceptional strength-to-weight ratio, high performance at elevated temperatures, high hardenability, outstanding corrosion resistance, good biocompatibility and excellent fatigue propagation properties [1,2,3,4,5].their poor tribological properties and high thermal expansion coefficient restrict their application [6,7], especially as structural materials in the extreme space environment.Recently, Zr has been noted for its ability to improve the mechanical properties of Ti alloys and a new Ti alloy comprising Ti-20Zr-6.5Al-4V (wt %, shortened to 20Zr hereafter) has been developed [8].The alloy exhibits higher tensile strength and hardness than the well-known Ti-6Al-4V alloy [8,9]. In this study, we selected 20Zr alloy annealed at 750 ◦ C for 2 h to investigate the anisotropy of the mechanical properties because it exhibits a balance of high strength and ductility [13].

Results

Conclusion