75wt.% Ag-25wt.% Pd 합금의 Ta첨가에 따른 미세조직변화와 기계적성질에 관한 연구 = A STUDY ON THE EFFECTS OF Ta ADDITION ON MECHANICAL PROPERTIES AND MICROSTRUCTURES OF 75Ag-25Pd ALLOY

다국어 초록 (Multilingual Abstract)

In study, mechanical properties and microstructures of 75wt.%Ag-25wt.Pd alloys with different amount of Ta additions from 0.1 to 1.0wt.% are investigated. With increasing Ta content grain size is reduced and tensile strength is increased. When 0.2wt.% Ta is added, reduction of the grain size is remarkable, and maximum tensile strength is achieved. With 0.6wt.% addition of Ta, fine primary crystals are found at the grain boundary after casting and tensile strength is slightly decreased. There is no significant microstructual changes at all heat treatment conditions. TEM, EPMA, and XRD analysis reveal that fine primary crystals are Pd₃Ta with tetragonal crystal structure. No apparent change of tensile strength is observed with different heat treatments.
Experimental results shows that Ta intermetallic particles formed in the melt of Ag-Pd alloy act as nucleation sites for solidification which results in the grain refinement. Addition of Ta more than 0.6wt.% reduces the tensile strength of the alloy by forming coarse Pd₃Ta in the melt. The Optimum amount of Ta addition on Ag-Pd alloy is 0.2wt.%, which reduce grain size about 42% and improve tensile strength up to 20% in comparison with Ag-Pd binary alloy without Ta.

목차 (Table of Contents)

• Ⅰ. 서론
• Ⅱ. 연구재료 및 방법
• Ⅲ. 연구성적
• Ⅳ. 총괄 및 고찰
• Ⅴ. 결론
• 참고문헌
• 영문초록