알루미늄청동의 미세조직과 기계적 성질에 미치는 Fe 및 Si 첨가의 영향

Abstract

The effects of iron and silicon additions on the microstructures and mechanical properties of aluminium bronze were investigated in this study. When 0.2wt.% Fe was added to the Cu-7.85wt.%Al mold cast round-bar specimens, its α phase had coarse dendrite structures and when 2.99wt.% Si was added to the Cu-7.85wt.%Al round-bar specimens as mold casting, its α phase had non-uniformly distributed needle structures. However, α phase had uniformly distributed needle structures in the Cu-6.93%Al-0.117%Fe-2.3%Si(wt.%) alloy. SEM-EDS point analysis distinguished Cu, Al, Fe and Si for the Cu-7%Al-0.8%Fe-2.5%Si(wt.%) centrifuged specimens, FeSI hard patticles wre distributed uniformly in the alloy’s matrix which had Al and Si as solid solution. The Vikers hardness of mold cast round-bar specimens was that : Cu-7.85%Al(wt.%) alloy was Hv 135.4 Cu-7.41%Al-0.2%Fe(wt.%) alloy Hv 103.2, Cu-7.78%Al-2.99%Si (wt.%) alloy Hv 345.0 and Cu-6.93%Al-0.117%Fe-2.3%Si(wt.%) alloy Hv 268.1. the Vickers hardness of centrifuged cylinder-shape specimens (Cu-7%Al-0.8%Fe-2.5%Si(wt.%) alloy) was Hv 236.5, tensile strength 727.3 N/㎟, yield strength 593.9 N/㎟, and elongation 8.6%. From the comparison of tensile strength of normalizing heat treated cylinder-shape specimens in the centrifugal cast Cu-7%Al-0.8%Fe-2.5%Si(wt.%), when the Al content was as high as 7.82wt.%, tensile strength was 781 N/㎟ and when the Al content was as low as 7.31wt.%, tensile strength was 681.5 N/㎟. A few Al content difference was verified to have huge impact on the tensile strength of aluminium bronze.