Metal Injection Molding 공정으로 제조된 W-7Ni-3Fe 텅스텐 중합금의 미세조직 및 기계적 특성에 미치는 열처리의 영향

• Published in: 대한금속·재료학회지, 56(10) Vol. 56; no. 10; pp. 727 - 733
• Main Authors: 윤성준, Seong-june Youn, 주연아, Yeun-ah Joo, 윤태식, Tae-shik Yoon, 이기안, Kee-ahn Lee
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.10.2018; 대한금속·재료학회
• Subjects: metal injection molding; microstructure; tensile properties; tungsten heavy alloy; W-7Ni-3Fe; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2018.56.10.727

This study investigated the microstructure and room temperature mechanical properties of W-7Ni- 3Fe (wt%) tungsten heavy alloy (as-fabricated) which was manufactured by metal injection molding (MIM). To identify the effect of heat treatment on the W-7Ni-3Fe alloy, its properties were compared after heattreatment (1,100 oC for 1 hour) in vacuum atmosphere. The initial microstructural observations confirmed that both the as-fabricated and heat-treated specimens were composed of W phase and γ(Ni, Fe) phase. Vickers hardness measurements were 363.7 Hv for the as-fabricated specimen and 387.2 Hv for the heat-treated specimen. Room temperature tensile strength was tested, and the yield strength of the as-fabricated and heattreated specimens were 698.3 and 714.0 MPa, and the ultimate tensile strengths were 760.8 and 960.0 MPa, respectively. The elongation of the two materials was 2.4% (as-fabricated) and 20.3% (heat-treated). It was found that additional heat treatment after MIM significantly improved the alloy’s mechanical properties. In addition, fracture surface observation results confirmed that the main crack propagated along the interface between the spherical W phase and γ(Ni, Fe) phase in the as-fabricated specimen, and traversed the W phase in the heat-treated specimen. Based on the above findings, this study also discusses the fracture mechanisms of tungsten heavy alloy manufactured with MIM. (Received August 9, 2018; Accepted August 31; 2018)