Enhanced strength-ductility synergy and mechanisms of heterostructured Ti6Al4V-Cu alloys produced by laser powder bed fusion

Abstract

Limited slip systems of structure always play a major role in hindering strength-ductility synergy improvement of titanium (Ti) alloys. To overcome the strength-ductility trade-off of Ti alloys, heterostructure is introduced into Ti6Al4V-xCu (x = 0, 1, 3, 5 wt.%) alloys produced by laser powder bed fusion (LPBF), and the formation mechanism and deformation behavior of heterostructures were investigated. The results showed that the monolithic ' in the LPBF-produced Ti6Al4V-xCu (wt%) alloys is decomposed into dual and " after heat treatment at 600–900 °C through ' + Ti2Cu matastable phase + ". The multistage transformation of ' to and " is driven by thermal activation (temperature > 800 °C), Cu addition and rapid cooling of water quenching. The heterostructure with and " in the LPBF-produced Ti6Al4V-5Cu alloy after heat treatment at 800 °C results in high tensile strength (∼1.3 GPa) and large elongation (∼15%). The enhanced strength-ductility synergy is attributed to the decomposition of brittle ' and Ti2Cu, as well the soft-hard heterostructure of " and . Moreover, the deformation twins (DTs) in " and the heterogeneous interfaces of and " can also improve the strength and ductility of the LPBF-produced Ti6Al4V-xCu alloys. These findings elucidate the influence of heterostructure ( and ") on strength and ductility, which is helpful for designing Ti alloys with excellent mechanical properties.

Keywords

Deformation twins, Heterostructure, Laser powder bed fusion, Mechanical behavior, Titanium alloy

Document Type

Journal Article

Date of Publication

9-1-2023

Volume

256

Publication Title

Acta Materialia

Publisher

Elsevier

School

School of Engineering / Centre for Advanced Materials and Manufacturing

RAS ID

61917

Funders

National Natural Science Foundation of China / Project of MOE Key Lab of Disaster Forecast and Control in Engineering in Jinan University / Guangzhou Basic and Applied Basic Research Foundation / Guang- dong Province Basic and Applied Basic Research Foundation / Guangxi Key Laboratory of Information Materials / Open Project Program of the State Key Laboratory of Mechanical Transmissions in Chongqing University / Fundamental Research Funds for the Central Universities

Comments

Li, K., Yang, J., Yi, Y., Liu, X., Liu, Y., Zhang, L. C., . . . Zhou, S. (2023). Enhanced strength-ductility synergy and mechanisms of heterostructured Ti6Al4V-Cu alloys produced by laser powder bed fusion. Acta Materialia, 256, article 119112. https://doi.org/10.1016/j.actamat.2023.119112

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Link to publisher version (DOI)

10.1016/j.actamat.2023.119112