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SiC 휘스커로 강화한 6061 Al 합금 복합재료의 기계적 특성에 미치는 열간압출의 영향
김준수,임수근 ( Jun Su Kim,Su Geun Lim ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.2
N/A Both cast and extruded composites of SiC whisker reinforced 6061 Al alloy matrix were fabricated by high pressure infiltration of the alloy melt into the SiC preform and subsequent hot extrusion of the composite ingots. The micro structures, age hardening behavior and mechanical properties have been examined on the both cast and extruded composites of SiCw/6061. The cast composites of SiCw/6061 were obtained in which SiC whiskers were randomly oriented. Hot extrusion of these cast composites lead to alignment of the whisker in the direction of extrusion. Strengthening effect of whisker in the extruded composites is lower than that of the cast composites. The cast composites of SiCw/6061 showed higher thensile strength and lower elongation than extruded composites of SiCw/6061 at all testing temperatures. Lower tensile strength and higher elongation of the extruded composites were attributable to fine grain structures in which grain boundary sliding occurred preferentially at elevated temperatures.
Composite Materials-: SiC 휘스커강화 2024 및 7075 알루미늄합금기 복합재료의 제조와 기계적 특성
임수근,김준수 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.2
Unidirectionally reinforced Al 2024 and Al 7075 composites with SiC whiskers were fabricated by high pressure infiltration technique and subsequent hot extrusion. The microstructure, age hardening behavior and mechanical properties of the composites were examined. Hot extrusion enabled the unidirectional alignment of whiskers, but substantial amount of whiskers was broken during extrusion. The whisker reinforcement tends to accelerate the age hardening, and decrease the amount of aging, due to the inhomogeneous precipitation of stable phases at the lattice defects in the matrix. The beneficial effect of whisker reinforcement was observed up to 473K. Above 573K, however, the mechanical properties of the composite were comparable to those of the unreinforced alloys, attributable to the enhanced grain boundary sliding due to the fine grain structure formed during hot extrusion.
AZ91 마그네슘 합금의 각종 음이온 용액중에서의 부식특성
김기원,김경호,허보영,임수근,안효준 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.12
The corrosion characteristics of AZ91 Mg alloy were studied in various anion-containing solutions. Through weight loss test, changes of corrosion potential under open circuit condition, changes of corrosion current density under potentiostatic condition and optical microscopy, effects of various anions on corrosion behaviours of AZ91 Mg alloy were investgated. It was found that chloride ion had two different effects on corrosion behaviours of AZ91 Mg alloy. When only chloride ions exist in water solution without any other anions, those make pitting corrosion, accelerate more rapidly. But when small amount of chloride ions exist with sulfate or nitrate ions, those make pitting corrosion occur slowly rather than in only sulfate or nitrate ions containing solution. These results were interpreted as competitive adsorption between chloride ion and sulfate or nitrate ion.