(南昌大学 材料科学与工程学院，南昌 330031)
摘 要: Cu-Ti合金因其高强度、高弹性、良好的抗应力松弛性能和较好的导电性，可广泛应用于各种导电弹性元件，是Cu-Be合金的理想替代材料。本文利用扫描透射电镜(STEM)研究了Cu-4Ti-1Al合金在不同温度时效时的相变特征，同时也对其时效性能进行了测定。结果表明：Cu-4Ti-1Al合金在(400 ℃, 1 h)时效后，过饱和的固溶体中溶质原子发生了明显的丛聚化或偏聚现象。随着时效时间的延长，丛聚化开始向有序化转变。成分调幅组织逐渐粗化，并形成了亚稳、共格的β′-Cu4Ti相，其和基体的位向关系为[001]p//[001]Cu和[100]p// Cu。Cu-4Ti-1Al合金在(600 ℃, 1 h)时效后，晶内以连续析出的β′-Cu4Ti相为主，晶界上有胞状组织出现。胞状组织团粒是由β-Cu4Ti平衡相和α固溶体层片相间组成。二者的位向关系为 ||(010) β和 ||[501] β。Cu-4Ti-1Al合金在(650 ℃, 1 h)时效后，晶内的析出相为粗大的棒状非共格相。晶界上不连续析出的胞状组织增加。Al的作用主要有三个：起到了固溶强化作用；推迟了有序化的发生；降低了合金的β′-Cu4Ti相共格固溶度线温度。
关键字: Cu-Ti合金；调幅分解；有序化；连续/不连续析出；胞状组织
（School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China）
Abstract:Cu-Ti alloys can be widely used in the electronic and elastic components and therefore have become the ideal substitute materials for Cu-Be alloys because of its high strength, high elasticity and good stress relaxation resistance. In this work, the phase transformation of Cu-4Ti-1Al alloy during aging at different temperatures was investigated by scanning transmission electron microscopy (STEM) and its aging properties were studied. The results show that obvious clustering occurs in supersaturated solid solution of Cu-4Ti-1Al alloy after aging at 400 ℃ for 1 h. With increasing aging time, clustering begins to transform into ordering. Meanwhile, the modulated structure of Cu-4Ti-1Al alloy coarsens gradually and the coherent and metastable β′-Cu4Ti precipitates continuously within the grains. The orientation relationship between β′-Cu4Ti and matrix is [001]p//[001]Cu and [100]p// Cu. After Cu-4Ti-1Al alloy aged at 600℃ for 1 h, cellular colonies containing α, a slightly supersaturated matrix and β-Cu4Ti phase appear at grain boundaries, while the β′-Cu4Ti precipitates within the grains. The orientation relationship between the cellular lamellae of α and β-Cu4Ti is ||(010) β and ||[501] β. After Cu-4Ti-1Al alloy aged at 650 ℃ for 1 h, the size and content of cellular structures precipitated by discontinuous decomposition increase and rod-shaped incoherent precipitates form inside grains. Al addition plays three roles as follows: (i) Al can harden the matrix by solution strengthening; (ii) It postpones ordering of Cu-4Ti-1Al alloy; (iii) It lowers the coherent solvus temperature of metastable β′-Cu4Ti phase.
Key words: Cu-Ti alloy; spinodal decomposition; ordering; continuous/discontinuous precipitation; cellular
