| 초음파 용탕 처리 및 냉각속도가 Al-18Si-4Cu-3Ni 피스톤용 합금의 미세조직과 고온인장특성에 미치는 영향 |
| 윤재희1,2, 조영희1, 정재길1, 이정무1, 박익민2 |
1재료연구소 실용화연구단 소재실용화연구실
2부산대학교 재료공학과 |
| Influence of Ultrasonic Melt Treatment and Cooling Rates on the Microstructural Development and Elevated Temperature Mechanical Properties of a Hypereutectic Al-18Si-4Cu-3Ni Piston Alloy |
| Jea-Hee Yoon1,2, Young-Hee Cho1, Jae-Gil Jung1, Jung-Moo Lee1, Ik Min Park2 |
1Implementation Research Division, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea
2Department of Materials Science and Engineering, Pusan National University, Busan 46269, Republic of Korea |
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Received: 21 October 2016; Accepted: 7 December 2016. Published online: 1 June 2017. |
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| ABSTRACT |
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The influence of ultrasonic melt treatment (UST) combined with a change in cooling rates on the microstructure and elevated temperature mechanical properties of a hypereutectic Al-18Si-4Cu-3Ni piston alloy was investigated. Microstructural observation confirmed that UST effectively refined the sizes of primary Si and intermetallic compounds (e.g. ε-Al3Ni) while promoting their homogeneous distribution. Besides the refinement of the constituent phases, the size of the dendrite arm spacing (DAS), which was hardly affected by UST, significantly deceased with increasing cooling rates. The refinement of the solidification structure in the alloy achieved through both UST and increased cooling rates resulted in an improvement in tensile properties, ultimate tensile strength and elongation in particular, after T5 heat treatment followed by overaging at 350 ℃. However, the elevated temperature yield strength of the alloy was not associated with the refinement, but was rather correlated with the 3-D interconnectivity, morphology and volume fraction of the primary Si. |
| Keywords:
hypereutectic Al-18Si casting alloy, ultrasonic melt treatment, microstructure, interconnectivity, elevated temperature tensile properties |
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