強化機理
黃金亮2, 田保紅2, 金志浩1
(1.西安交通大學 材料科學與工程學院，
西安 710049；
2.洛陽工學院 材料工程系， 洛陽 471039)
摘 要: 利用透射電鏡及X射線衍射研究了Cu-Ni-Si合金時效早期的組織轉(zhuǎn)變規(guī)律。結(jié)果表明：該合金在時效早期，過飽和固溶體首先發(fā)生成分調(diào)幅，形成貧、富溶質(zhì)區(qū)，隨后，溶質(zhì)富集區(qū)發(fā)生有序化，在450℃時效4h左右富溶質(zhì)區(qū)內(nèi)形成Ni2Si相，形成的Ni2Si相與基體呈共格關系，但由于晶體結(jié)構(gòu)同基體差別較大，仍以Orowan機制提高合金強度。利用位錯理論計算出450℃時效2h的調(diào)幅組織的強化效應為342MPa，450℃時效4h形成的Ni2Si相的強化效應為405MPa，該數(shù)值與實驗結(jié)果非常吻合。
關鍵字: Cu-Ni-Si合金；相變；時效；調(diào)幅分解；應變強化指數(shù)
KANG Bu-xi2, HUANG Jin-liang2,
TIAN Bao-hong2, JIN Zhi-hao1
（1.School of Materials Science and Engineering, Xi′an Jiaotong University,
Xi′an 710049, China;
2. Department of Materials Engineering,Luoyang Institute of Technology,
Luoyang 471039, China）
Abstract:The transformation of the early stage of aging in Cu-3.2Ni-0.75Si alloy was investigated by means of transmission electron microscope and X-ray diffraction . It is shown that the supersaturated solution Cu-Ni-Si alloy first decomposes into solute-rich and solute-depleted zones by spinodal mechanism, then the solute-rich zones form Ni2Si phases which remain coherent with the matrix. Due to the significant difference in structure between the matrix and the precipitate, an Orowan type strengthening mechanism is believed to still operate. The strengthening effect of the spinodal structure aged at 450℃ for 2h is calculated to be 342MPa by using dislocation theory, and that of the Ni2Si phase precipitated in aging at 450℃ for 4h is about 405MPa, which are quite consistent with the experimental data.
Key words: Cu-Ni-Si alloy; transformation; aging; spinodal decomposition; work-hardening rate
