저온 분사 공정으로 제조된 초고강도 Cu 벌크 소재의 인장 및 압축 변형 거동

• Published in: 대한금속·재료학회지, 58(11) Vol. 58; no. 11; pp. 759 - 767
• Main Authors: 김영균, Young-kyun Kim, 이기안, Kee-ahn Lee
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.11.2020; 대한금속·재료학회
• Subjects: cold spray; compression; constitutive model; deformation behavior; high-strength; pure cu; tensile; 재료공학
• ISSN: 1738-8228; 2288-8241

In this study, high-strength pure Cu bulk material was manufactured using a cold spray additive manufacturing process, and its microstructure, tensile and compressive deformation behaviors were investigated and compared. The cold spray additive manufactured Cu bulk material showed a heterogeneous grain structure consisting of fine-grains and coarse-grains, and only α - Cu single phase was identified. The cold spray Cu exhibited yield strengths of ~415 MPa in tensile- and compression tests, indicating that it had similar mechanical properties in different deformation modes. The yield strength values were similar to that of Cu manufactured by equal channel angular pressing (ECAP), a severe plastic deformation (SPD) method which enables ultra-high strength. Concerning tensile characteristics, the cold sprayed Cu exhibited partial plastic deformation that has not been reported to date. In addition, some nano-sized dimples, suggesting metallurgical bonding, were also found in the fracture surface. Regarding compression characteristics, the strain softening phenomenon, which is not a general tendency in room temperature deformation, appeared. This unique softening behavior was attributed to dynamic recovery and dynamic recrystallization during compression testing. Based on the above results, we discuss the tensile/compressive deformation behavior of the cold spray Cu bulk material, and predict compressive deformation behavior considering the constitutive equation. (Received August 26, 2020; Accepted September 9, 2020)