(南昌大學 材料科學與工程學院，南昌 330031)
摘 要: Cu-Ti合金因其高強度、高彈性、良好的抗應力松弛性能和較好的導電性，可廣泛應用于各種導電彈性元件，是Cu-Be合金的理想替代材料。本文利用掃描透射電鏡(STEM)研究了Cu-4Ti-1Al合金在不同溫度時效時的相變特征，同時也對其時效性能進行了測定。結果表明：Cu-4Ti-1Al合金在(400 ℃, 1 h)時效后，過飽和的固溶體中溶質原子發(fā)生了明顯的叢聚化或偏聚現象。隨著時效時間的延長，叢聚化開始向有序化轉變。成分調幅組織逐漸粗化，并形成了亞穩(wěn)、共格的β′-Cu4Ti相，其和基體的位向關系為[001]p//[001]Cu和[100]p// Cu。Cu-4Ti-1Al合金在(600 ℃, 1 h)時效后，晶內以連續(xù)析出的β′-Cu4Ti相為主，晶界上有胞狀組織出現。胞狀組織團粒是由β-Cu4Ti平衡相和α固溶體層片相間組成。二者的位向關系為 ||(010) β和 ||[501] β。Cu-4Ti-1Al合金在(650 ℃, 1 h)時效后，晶內的析出相為粗大的棒狀非共格相。晶界上不連續(xù)析出的胞狀組織增加。Al的作用主要有三個：起到了固溶強化作用；推遲了有序化的發(fā)生；降低了合金的β′-Cu4Ti相共格固溶度線溫度。
關鍵字: Cu-Ti合金；調幅分解；有序化；連續(xù)/不連續(xù)析出；胞狀組織
（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
