Development of New Type Cu Base Alloys Obtained by Controling Ordering and Phase Separation

Cu-Al-Mn合金的β相存在A2/B2/D 03/L21有序-无序转变、磁转变和有序相的相分离等多种相变。本研究的目的是利用这些转变来开发一些新型的铜基合金。实际上，高强度铜合金，形状记忆（SM）合金和巨磁电阻（GMR）薄膜在本研究中进行了研究。本研究获得的所有结果如下：（1）高强度铜合金：在Cu-13%Al-15%Mn-5%Ni合金中，由于在300℃时效，获得了超过1000 MPa的非常高水平的抗拉强度。TEM观察表明，时效态试样的显微组织为尺度很细的贝氏体组织。由于除了Cu-Be合金外，在Cu基合金中还没有如此高水平的强度的报道，因此本合金具有成为新型高强度Cu基合金的潜力。(2)研究了合金元素对形状记忆合金的可加工性、Ms温度和形状记忆性能的影响。结果表明，析出物降低了塑性，Si、Au和Co提高了Ms温度，SM性能受晶粒尺寸和织构的强烈影响。(3)研究了不同成分的Cu-Al-Mn合金的巨磁电阻效应。结果表明，体积分数为Cu 2 MnAl：Cu 3Al =3：7的Cu-25%Al-10%Mn合金的巨磁电阻率最高，超过4%。

It is known that there are many kinds of transformations, such as A2/B2/D03/L21 order-disorder transitions, magnetic transition and phase separation in their ordered phases, in the β phase of the Cu-Al-Mn alloys. The purpose of this study is to develop some new types of Cu base alloys using these transformations. Actually high strength Cu alloys, shape memory (SM) alloys and giant magnetoresistance (GMR) thin films were examined in the present study. All the results obtained in this study are listed as follows :(1) High Strength Cu Alloys :In the Cu-13%Al-15%Mn-5%Ni alloys, very high level of tensile strength over 1000MPa were achieved due to aging at 300℃. According to TEM observation, it is seen that the microstructure of the as-aged specimens has a kind of bainate structure with very fine scale. Since such the high level of strength in the Cu base alloys has not been reported except the Cu-Be alloys, the present alloys have a potential for a new kind of high strength Cu base alloys.(2) Shape Memory AlloysEffects of alloying elements on the fabricability, Ms temperature and SM properties were examined. It was clarified that the precipitates decrease ductility, Si, Au and Co increase the Ms temperature and the SM properties are strongly influenced by grain size and texture.(3) Giant Magnetoresistance Thin FilmsGMR properties of Cu-Al-Mn alloys with wide range of compositions were examined. It was clarified that the Cu-25%Al-10%Mn alloy which has the volume fraction of Cu2MnAl:Cu3Al=3:7 shows the highest GMR ratio over 4%.Based on the above results, joint projects for practical applications with some companies are running.