The purpose of this study is to develop a zirconium-based alloy with low modulus and magnetic susceptibility to prevent the stress-shielding effect and the generation of artifacts. Zr-7Cu-xSn (x = 1, 5, 10, 15 mass%) alloys are prepared by an arc melting process. Microstructure characterization is performed by microscopy and X-ray diffraction. Mechanical properties are evaluated using micro Vickers hardness and compression test. The magnetic susceptibility is evaluated using a SQUIDVSM. The average magnetic susceptibility value of the Zr-7Cu-xSn alloy is 1.176 × 108 cm3g1. Corrosion tests of zirconiumbased alloys are conducted through polarization test. The average Icorr value of the Zr-7Cu-xSn alloy is 0.1912 A/cm2. The elastic modulus value of 14 ~ 18 GPa of the zirconium-based alloy is very similar to the elastic modulus value of 15 ~ 30 GPa of the human bone. Consequently, the Sn added zirconium alloy, Zr-7Cu-xSn, is very interesting and attractive as a biomaterial that reduces the stress-shielding effect caused by differences of elastic modulus between human bone and metallic implants. In addition, this material has the potential to be used in metallic dental implants to effectively eliminate artifacts in MRI images due to low magnetic susceptibility.

In this study, Cu-5Ni-10Sn(wt%) spinodal alloy was manufactured by gas atomization spray forming, and the microstructural features and mechanical properties of Cu-5Ni-10Sn alloy have been investigated during homogenization, cold working and age-hardening. The spray formed Cu-5Ni-10Sn alloy consisted of an equiaxed microstructure with a mixture of solid solution -(CuNiSn) grains and lamellar-structure grains. Homogenization at and subsequent rapid quenching formed a uniform solid solution -(CuNiSn) phase. Direct aging at from the homogenized Cu-5Ni-10Sn alloy promoted the precipitation of finely distributed ' or phase throughout the matrix, resulting in a significant increase in microhardness and tensile strength. Cold working prior to aging was effective in strengthening Cu-5Ni-10Sn alloy, which gave rise to a maximum tensile strength of 1165 MPa. Subsequent aging treatment slightly reduced the tensile strength to 1000-1100 MPa due to annealing effects.

In this study, Cu-10Sn and Cu-10Sn-2Ni-0.2Si alloys have been manufactured by spray casting in order to achieve a fine scale microstructure and high tensile strength, and investigated in terms of microstructural evolution, aging characteristics and tensile properties. Spray cast alloys had a much lower microhardness than continuous cast billet because of an improved homogenization and an extended Sn solid solubility. Spray cast Cu-Sn-Ni-Si alloy was characterized by an equiaxed grain microstructure with a small-sized (Ni, Si)-rich precipitates. Cold rolling of Cu-Sn-Ni-Si alloy increased a tensile strength to 1220 MPa, but subsequent ageing treatment reduced a ultimate tensile strength to 780 MPa with an elongation of 18%.

For the fabrication of core-shell structure bimetallic lead-free solder balls, both the critical temperature (Tcr) for the phase separation of two immiscible liquid phases and the temperature coefficient of the interfacial tension between the two separated liquid phases are required. In order to obtain this information, the temperature dependence of the surface tension of 60%Bi-24%Cu-16%Sn(-REM) alloys was measured using the constrained drop method. The slope of the temperature dependence of the surface tension changed clearly at a critical temperature for the separation of two immiscible liquid phases. The critical temperature of the 60%Bi-24%Cu-16%Sn alloy was estimated to be 1097K. An addition of 0.05% Ce decreased the critical temperature to 1085K, whereas that of 0.05% La increased it to 1117K. It was found that the surface tension and its temperature coefficient of the 60%Bi-24%Cu-16%Sn alloy were slightly increased by the addition of 0.05% Ce and 0.05% La. In addition, additions of Ce and La increased the temperature coefficient of the interfacial tension.

A new method has been developed to fabricate microcomponents by a combination of photolithography and sintering of metallic powder mixtures, without the need for compression and the addition of Mg. This involves (1) the fabrication of a micromould, (2) mould filling of the powder/binder mixture, (3) debinding and (3) sintering. The starting powdered materials consisted of a mixture of aluminium powder(average size of 2.5 um) and alloying elemental powder of Cu and Sn(less than 70nm), at appropriate proportions to achieve nominal compositions of Al-6wt%Cu, Al-6wt%Cu-3wt%Sn. This paper presents detailed investigation of debinding behaviour and microstructural development.

기계적 합금화 공정으로 제조한 1μm 이하 크기의 Cu6Sn5를 63Sn-37Pb 솔더합금에 첨가하여, Cu6Sn5 첨가분율에 따른 미세구조와 기계적 성질을 Cu를 첨가한 솔더합금과 비교하였다. Cu6Sn5를 첨가한 솔더합금에 비해 Cu를 첨가한 솔더합금에서 첨가분율에 따른 Cu6Sn5 함량의 증가와 크기 성장의 정도가 더욱 현저하게 발생하였다. Cu를 첨가한 솔더합금에 비해 Cu6Sn5를 첨가한 솔더합금에서 항복강도의 향상 정도는 저하하였으나, 더 높은 최대인장강도를 얻을 수 있었다. 1~9 vol%의 Cu6Sn5를 첨가함에 따란 63Sn-37Pb 솔더합금의 항복강도가 23 MPa에서 36MPa 정도로 증가하였으며, 1~9vol%의 Cu 첨가시에는 항복강도가 40 MPa로 향상되었다. 각기 5 vol%의 Cu6Sn5와 Cu를 첨가함에 따라 63Sn-37Pb 솔더합금의 인장강도가 34.7 MPa에서 45.3MPa and to 43.1 MPa로 향상되었다.

분말야금법으로 제조된 Cu-7.5Ni-5Sn 합금의 용체화 및 시효 열처리 조건에 따른 기계적 특성의 변화를 관찰하였다. As-received 상태의 Cu-7.5Ni-5Sn 합금을 시효한 경우에는 시효 20분 후에 γ' 상의 석출에 의한 강도 증가를 나타내는데 반해, 재용체화 처리된 시편에서는 시효 수십초부터 스피노달 분해에 의한 급격한 강도의 증가를 나타내고 있다. 그러나 전체적인 인장강도는 재용체화 처리를 행한 경우에 비해 as-received 상태에서 등온 시효한 경우가 더욱 우수한 것으로 나타났다. 이러한 현상은 재용체화 처리에 의한 결정립 성장에 기인한 것으로 사료된다. As-received 상태의 Cu-7.5Ni-5Sn 합금을 장시간 시효하게 되면 결정립계에 불연속 석출물이 생성되었으며, 이러한 불연속 석출물의 생성과 성장은 열처리 조건에 영향을 받는 것으로 관찰되었으며, 합금의 최종 기계적 성질에 크게 영향을 미치는 것으로 판단된다.

동과 동을 저온에서 단시간내에 접합시키는 가능성을 검토하기 위해서 직류 자기 스퍼터링을 이용한 코팅한 주석 및 주석-잡 합금층을 중간층으로 사용하였다. 접합은 대기중 200-350˚C의 온도에서 수행되었고 접합온도에 도달직후 바로 냉각하였다. 접합 계면에는 액상의 주석과 고상의 동간의 반응에 의해 n-상(Cu6Sn5) 및 ε-상(Cu3Sn)으로 구성된 금속간화함물 층이 형성되었다. 전단강도로 측정된 접합강도는 접합온도에 따라 비례적으로 증가하지만 300˚C 이상에서 감소하였다. 접합강도는 2.8-6.2MPa 범위로 나타났으며, 중간층합금 성분에 따른 접합계면에서의 금속간화합물의 생성거동과 관련지어 설명되었다. 실험결과 실용적인 접합법으로서 저온 단시간 접합의 가능성이 확인되었다.