( 1. 西安理工大學機械工程系， 西安 710049；
2. 河南科技大學 材料學院， 洛陽 471039)
摘 要: 利用透射電鏡、 顯微硬度法和電導率法，研究了Cu-Ni-Si二次時效過程中顯微組織、硬度及導電率變化情況。 結(jié)果表明： 二次時效可使合金在較短的時效時間內(nèi)獲得更高的導電率， 經(jīng)預時效后冷變形的合金， 溶質(zhì)原子可借助密集且分布均勻的位錯網(wǎng)絡由銅基體快速傳輸至析出物處或析出物的形核部位完成析出過程，使銅基體得到快速的凈化， 從而獲得較高的導電性。 Cu-3.2Ni-0.75Si合金經(jīng)預時效+變形后的時效過程中， 可發(fā)生原位再結(jié)晶和不連續(xù)再結(jié)晶兩種形式的再結(jié)晶。再結(jié)晶的形式主要決定于預時效時析出相的大小和冷變形的程度， 穩(wěn)定細小的析出相促使原位再結(jié)晶的發(fā)生， 原位再結(jié)晶使合金微觀組織中析出相比較細小， 因而保持較高的硬度；亞穩(wěn)的析出相在再結(jié)晶過程中將向穩(wěn)定相轉(zhuǎn)變， 相變動力與形變儲存能共同作用促使合金發(fā)生不連續(xù)再結(jié)晶， 使合金硬度迅速下降， 析出相快速粗化。
關(guān)鍵字: 銅合金； 時效； 再結(jié)晶； 預時效； 析出相
Cu-Ni-Si alloy during two-step aging
LIU Ping2, LIU Hong-zhao1
（ 1. Department of Mechanical Engineering,
Xi′an University of Technology，
Xi′an 710049, China;
2. School of Materials Engineering,
Henan University of Science and Technology,
Luoyang 471039, China）
Abstract: In the case of two-step aging of Cu-Ni-Si alloy, the variation in microstructure, micro-hardness and electrical conductivity were investigated by TEM analyses, electrical resistivity and micro-hardness measurements. It is concluded that a higher electrical conductivity can be obtained by two-step aging treatment directly. The reason for this can be explained that the solute atoms of the alloy, which was cold rolled after pre-aging, could transmit from matrix to the precipitates or their nucleus easily through the path formed by the displacement networks which are distributed in the alloy homogenously and intensively. The situ recrystallization and discontinuous recrystallization can take place in Cu-3.2Ni-0.7Si for the effects of pre-aging combined with after-deformation-aging treatment. The result of the recrystallization in the aging process was dominated by both the size of pre-aging precipitation phase and the extend of cold deformation. It can be seen that a higher micro-hardness in the alloy corresponds to a microstructure with a fine and stable phase, which further promote the situ recrystallization taking place. However metastable precipitation phase formed during recrystallization will transform to stable phase and, in the case of discontinuous recrystallization affected by the combination of phase transformation kinetics and strain-energy, a rapid decreasing in micro-hardness corresponding to the coarse precipitation phase formed in the process will take place subsequently.
Key words: copper alloy; ageing; recrystallization; pre-ageing; precipitation
