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용탕단조한 미세강선 보강 알루미늄 복합재료의 미세조직에 대한 고찰
정봉용,이인우,박흥일,김준수,김명호 ( Bong Yong Jeong,In Woo Lee,Heung Il Park,Jun Su Kim,Myung Ho Kim ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.5
N/A Aluminum matrix composites reinforced by fine steel wires were fabricated by squeeze casting process. Preforms made of fine steel wires were prepared with different surface conditions, namely uncoated(TN), carbo-nitriding treated(TT), and brass coated(TA). Squeeze casting were performed under the pressure of 1500㎏/㎠ for 3min. during solidification, and pouring temp. of the melt being 750℃ and the steel mold being preheated at 250℃. Microstructural characteristics were evaluated, particularly concerned with the effect of the surface conditions of the preforms. The results obtained from this study are like these. TN specimens show partially non-wetted regions, due to easy formation of oxides on the surface of the fine steel wires. TT specimens show no interfacial reaction between the steel wires and the aluminum alloy matrix, possibly due to the formation of carbo-nitrided zone on the surface of the steel wires. TA specimens show excellent wettabillity between the reinforced steel wires and the aluminum alloy matrix and very thin interfacial zone is formed between them. During the solution hardening treatment of TA specimens, thickness of the interfacial reaction zones were increased with the solution treating time. TA specimens show typical ductile fracture in tensile test, but TT specimens show brittle fracture possibly due to the formation of the brittle hard surface on the steel wires during carbo-nitriding treatments. TA specimens which were reinforced with 40 vol.% of the fine steel wires exhibit high tensile strength of 77.l㎏f/㎟ and impact value of 8.l㎏f-m/㎠.
Ta/Fe-C-(Si) 주조접합재에서 동온열처리시 계면반응층의 성장에 관한 연구
김민영,안용식,박흥일,정병호,이성열,김무길 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.9
200㎛ thick Ta thin sheets and Fe-C-(Si) alloys with different chemical compositions, and interfacial reaction was investigated. The growth of carbide layer formed at the interface were cast-bonded after isothermal heat treatment at 1173K, 1223K, 1273K and 1323K for various times was investigated. The carbide formed at the interface was TaC, its chemical composition was 91.5wt.%Ta-6.6wt.%C-1.9wt.%Fe, and its hardness was ranging from 1820 to 1970Hv. The thickness of TaC layer was increased linearly in proportional to the heat treating time. Therefore, it was suggested that the growth of TaC layer was controlled by the interfacial reaction. The growth rate constant of TaC layer was slightly increased with increase of carbon content when the silicon content is similar in the cast irons. However, as silicon content increases with in case of almost same amount of carbon content, the growth of TaC layer was greatly retarded. The calculated activation energy for the growth of TaC layer was varied in the range of 278.1∼329.1kJ/㏖ with the compositions of cast irons. The activation energy was shown to be a tendency to increase with an increase of silicon content in cast iron.