확산접합된 Ni기 합금 Hastelloy X에 미치는 후열처리 영향 |
사인진1,*, 황종배2, 홍순익2, 김응선1, 김민환1 |
1한국원자력연구원 VHTR 기술개발부 2충남대학교 신소재공학과 |
Effect of Heat Treatment on the Diffusion-Bonded Ni-Base Alloy Hastelloy X |
Injin Sah1,*, Jong-Bae Hwang2, Sun-Ig Hong2, Eung-Seon Kim1, Min-Hwan Kim1 |
1VHTR Technology Development Division, Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea 2Department of Materials Science & Engineering, Chungnam National University, Daejeon 34134, Republic of Korea |
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Received: 18 April 2016; Accepted: 23 August 2016. Published online: 2 February 2017. |
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ABSTRACT |
The effect of post-bond heat treatment (PBHT) on diffusion-bonded polycrystalline Ni-base alloy Hastelloy X (Ni-22Cr-18Fe-8Mo) was evaluated in this study. Diffusion bonding was conducted under a compressive pressure of 14 MPa in the temperature range of 1100-1200 ℃. While (Cr,Mo)-rich and (Mo,Si)-rich precipitates were developed along the interface at 1100 ℃, the precipitates were dissolved and grain boundary migration across the interface occurred above 1150 ℃. As the dissolution of precipitates is related to the temperature rather than compressive pressure, a modified diffusion bonding condition (1120 ℃/10 MPa) was applied. Brittle fracture with low tensile ductility was observed at the testing temperature of 700 ℃, but substantial recovery of ductility was achieved up to a testing temperature of 900 ℃ through PBHT (1180 ℃/1 h). The reduction of discontinuity at the interface was found to bring about the ductile behavior at high temperature. |
Keywords:
metals, diffusion bonding, grain boundary, tensile test, hastelloy X |
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