Synergistic Strength–Ductility Improvement in an Additively Manufactured Body-Centered Cubic HfNbTaTiZr High-Entropy Alloy via Deep Cryogenic Treatment

Abstract

HfNbTaTiZr high-entropy alloy has wide application prospects as a biomedical material, and the use of laser additive manufacturing can solve the forming problems faced by the alloy. In view of the characteristics of the one-time forming of additive manufacturing methods, it is necessary to develop non-mechanical processing modification methods. In this paper, deep cryogenic treatment (DCT) is first applied to the modification of a HEA with BCC structure, then the post-processing method of DCT is combined with laser melting deposition (LMD) technology to successfully realize the coordinated improvement of forming and strength–ductility synergistic improvement in lightweight Hf0.25NbTa0.25TiZr alloy. The final tensile strength of the alloy after DCT treatment is 25% higher than that of the as-cast alloy and 11% higher than that of the as-deposited alloy, and the elongation is increased by 48% and 10%, respectively. In addition, DCT also achieves induced phase transition without additional deformation.

Keywords

• laser melting deposition
• high entropy alloy
• deep cryogenic treatment
• 3D printing
• defects
• strength–ductility synergistic improvement