Enhancing the plasticity of HfZrTiCr_x alloys by forming single phase solid solutions via reducing Cr content

ABSTRACT

The solid solution design strategy bolsters the comprehensive mechanical properties of high/medium entropy alloys (H/MEAs), yet its utilisation within hexagonal close-packed (HCP) H/MEAs remains notably limited. Here, exploring the impact of reduced Cr content (x = 0.3, 0.1, and 0) from the HfZrTiCr_0.5 prototype alloy, our study successfully obtained a novel HCP single phase MEA and investigated the relationship between microstructure and mechanical properties. Decreasing Cr content led to the diminishing presence of the Laves phase, culminating in a single HCP phase solid solution at x = 0.1. The Laves phase, arising from negative enthalpy between Cr and other elements and lower atomic radius of Cr, acted as crack initiation sites, resulting in brittle fracture (x = 0.5) alloy and limited plasticity strain of 3.5% (x = 0.3). Conversely, the HfZrTiCr_0.1 alloy exhibited impressive combined yield strength (1360 MPa) and plasticity strain (14.5%), attributed to prominent solid solution strengthening and enhanced dislocation movement within the solid solution structure. These findings offer insights into manipulating Cr content to form HCP solid solution structures, potentially broadening solid solution alloy design strategies for superior mechanical properties in HCP H/MEAs.

GRAPHICAL ABSTRACT

KEYWORDS:

• HCP high/medium entropy alloys
• solid solution structure
• Laves phase
• mechanical properties

Acknowledgements

Lin Han: Writing – original draft, Investigation, Chenlei Shen: Formal analysis, Feng Jiang: Visualisation, Boqiang Wu: Writing – review & editing, Gongji Yang: Writing – review & editing, Mingqin Xu: Writing – review & editing, Investigation. Jiaojiao Yi: Writing – review & editing, Investigation.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data will be made available on request.

Additional information

Funding

Financial supports from the Natural Science Foundation of the Jiangsu Higher Education Institutions of China [23KJD430005], Changzhou Science and Technology Bureau [CJ20235060], Zhongwu Research and Innovation Team Project of Jiangsu University of Technology [grant number 202101001], Changzhou Science and Technology Bureau [Young Elite Scientists Sponsorship Program] and Graduate Practice and Innovation Projects of Jiangsu University of Technology [XSJCX22_06] are gratefully acknowledged.