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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.
CaCN2 첨가에 의한 AM60 마그네슘 합금의 결정립 미세화 및 기계적 성질
엄정필,정승규,임수근,신희택,정득수 ( Jeong Pil Eom,Seong Kyu Jeong,Su Geun Lim,Hee Taek Shin,Deuk Soo Jeong ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.4
N/A Effects of CaCN₂ addition on the grain refinement in the AM60 magnesium ingots were investigated. The effects of the CaCN₂ are estimated with different inoculation temperatures, inoculation contents, and holding time to find out the optimum condition. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The melting and casting apparatus is specially designed for magnesium alloys. The grain size of AM60 magnesium alloy decreased significantly with an increase in CaCN₂ content and, at 0.8 wt% CaCN₂ or more, grain size becomes constant at about 85 ㎛. The optimum condition was obtained in the 0.8 wt% CaCN₂ for holding molten metal of 30 min. at the temperature of 710˚C. The tensile properties of AM60 magnesium alloys were improved due to grain refinement by addition of CaCN₂. In the optimum condition, the yield strength, tensile strength and elongation were σ_(0.2)= 107 MPa, σ_(T.S)=234 MPa and e=14.2%. The variation of stress with strain obeyed the relationship of the σ= Kε^n. The strain-hardening exponent, n and strength coefficient, K obtained in the 0.8 wt% CaCN₂ added AM 60 magnesium alloy were n=0.21 and K=390 MPa. (Received May 28, 1998)
AZ31 마그네슘합금의 결정립 미세화 및 기계적 특성에 미치는 Ca 첨가의 영향
김청림 ( Kim Cheong Lim ),엄정필 ( Eom Jeong Pil ),임수근 ( Im Su Geun ),박원욱 ( Park Won Ug ),유봉선 ( Yu Bong Seon ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.5
N/A Effects of Ca addition on grain refinement, microstructure and mechanical properties of AZ31 Mg alloy were investigated. Due to Ca addition to Mg alloy (AZ31), the microstructure was refined, the quantity of Mg_(17)Al_(12) phase was reduced, and new Al₂Ca phase was formed. The tensile property of AZ31 was increased with the minor addition of Ca, but was decreased rapidly over 0.2 wt.% of Ca content. The AL₂Ca phase was considered to be detrimental to the mechanical property of AZ31 Mg alloy.
Am60 마그네슘 합금의 결정립 미세화에 미치는 탄소접종제 C2Cl6 첨가의 영향
엄정필(Jeong Pil Eom),정승규(Seong Kyu Jeong),임수근(Su Geun Lim),신희택(Hee Taek Shin) 한국주조공학회 1999 한국주조공학회지 Vol.19 No.3
The effects of C₂Cl_6 addition on the grain refinement of AM60 magnesium alloy were investigated. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The effects of the C₂Cl_6 were estimated with various inoculation temperatures, inoculation contents, and holding times to find out the optimum conditions. The grain size of AM60 magnesium alloy decreased significantly with an increase in C₂Cl_6 content and, over 0.6 wt% C₂Cl_6 or more, grain size constant at about 94 ㎛. The optimum condition was obtained in the 0.6 wt% C₂C_(16), holding for 30 min. at 740˚C The tensile properties of AM60 magnesium alloys were improved due to grain refinement by the additions of C₂Cl_6 In the optimum condition, the yield strength, tensile strength and elongation were σ_(0.2) = 107 MPa, σ_(T.S) = 231 MPa and e = 1 4%, respectively. The variation of stress with strain obeyed the relationship of the σ= Kε^n. The strain-hardening exponent, n, and strength coefficient, K were n = 0.22 and K = 380 MPa. (Received March 30, 1999)
Ca첨가 반응고 AZ31 마그네슘 합금의 재가열에 따른 미세조직 변화
김희경 ( Hee Kyung Kim ),성봉학 ( Bong Hak Seong ),반근호 ( Geun Ho Van ),김대환 ( Dae Hwan Kim ),성영록 ( Yeong Rok Seong ),임수근 ( Su Gun Lim ) 한국주조공학회 2012 한국주조공학회지 Vol.32 No.2
In this study, we are aimed to prevent grain growth of semi-solid AZ31 magnesium alloys during reheating process. The semisolid AZ31+(Ca) billets were investigated by using metallographic analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy in order to elucidate the effect of Ca addition during reheating process. The grain growth of semisolid AZ31+(Ca) billet was reduced with increasing Ca content during reheating. The grain size of AZ31+(Ca) billet decreased with increasing volume fraction of Al2Ca particles. The grain growth rate constant K calculated by Oswald ripening LSW theory in AZ31+1.5wt.% Ca billet was the lowest 129.
급냉응고법에 의한 Al-9Zn-2.5Mg-1Cu-X P/M재의 제조 및 성질
임수근 慶尙大學校生産技術硏究所 1990 生産技術硏究所論文集 Vol.6 No.-
Rapidly solidified flakes of 7090 based aluminum alloys containing transition metals were produced by atomizing the alloy melt and subsequent splat quenching onto a water-cooled copper single roll. Consolidation of these flakes was done by cold pressing, degassing and hot extrusion at a reduction ratio of 25 to 1. As splat-quenched flakes showed cellular structure, consisting of primary phase and eutectic. The hardness of flakes and P/M materials increased with the addition of transition metals due to fine dispersion of their eutectic compounds. Mn was most effective for strengthening 7090 based alloy by the addition of transition metals. Tensile strength of T6 materials with 6 wt% Mn addition was 817MPa, and that of 2 wt% Mn addition was 787 Mpa. Furthermore, Mn bearing materials showed appreciably higher specific strength and specific elastic modulus than Ti alloy in room temperature.
기계적 합금화에 의한 세라믹 입자분산 2024 알루미늄 합금의 성질
임수근,관우신,김자순일 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.9
A study has been made of the crystallography and thermal stability of Cu-Zn-Al Shape Memory Alloys. The structure and the phase transformation of the alloys were studied by X-ray diffractometer, electron microscopy and resistivity measurement. The damping characteristics of them were also measured. The Ms temperatures varied from -61℃ to 77℃ with concentration of Zn and Al. The cystallographic structure of the parent phase and martensite was found to be DO₃(or L2₁) and modified 18R(β=88°) respectively. When aged at temperatures ranged from 250 to 350℃, the transformation temperatures were lowered and a maximum hardness was obtained. The aged Cu-26Zn-4.75Al and Cu-21Zn-6Al alloys had the structure of mixture of αand βwhereas the Cu-14.9Zn-8Al alloy had a and r structures. The Cu-14.9Zn-8Al alloy had a considerably higher thermal stability than others.
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.