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

研究表明，在铜铝锰合金的β相中存在A2/B2/D03/L21有序-无序转变、磁性转变和有序相中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。本文研究了高强度铜合金、形状记忆(SM)合金和巨磁电阻(GMR)薄膜。研究结果如下：(1)高强度铜合金：在Cu-13%Al-15%Mn-5%Ni合金中，在300℃时效条件下，抗拉强度可达1000 Mpa以上。通过透射电子显微镜观察发现，时效后的组织为细小鳞片的贝氏体组织。由于除CuBe合金外，铜基合金中还没有如此高的强度水平的报道，因此本合金有可能成为一种新型的高强度铜基合金。(2)形状记忆合金研究了合金元素对可加工性、Ms温度和SM性能的影响。结果表明，析出物降低了延展性，Si、Au和Co提高了合金的Ms温度，晶粒度和织构对SM性能有很大的影响。(3)研究了不同成分范围的Cu-Al-Mn合金的巨磁电阻薄膜的GMR性能。结果表明，体积分数为Cu2MnAl：Cu3Al=3：7的Cu-25%Al-10%Mn合金具有最高的巨磁电阻比，超过4%。基于上述结果，与一些公司进行了实际应用的联合项目。

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.