强化机理
(1.西安交通大学 材料科学与工程学院，
西安 710049；
2.洛阳工学院 材料工程系， 洛阳 471039)
摘 要: 利用透射电镜及X射线衍射研究了Cu-Ni-Si合金时效早期的组织转变规律。结果表明：该合金在时效早期，过饱和固溶体首先发生成分调幅，形成贫、富溶质区，随后，溶质富集区发生有序化，在450℃时效4h左右富溶质区内形成Ni2Si相，形成的Ni2Si相与基体呈共格关系，但由于晶体结构同基体差别较大，仍以Orowan机制提高合金强度。利用位错理论计算出450℃时效2h的调幅组织的强化效应为342MPa，450℃时效4h形成的Ni2Si相的强化效应为405MPa，该数值与实验结果非常吻合。
关键字: Cu-Ni-Si合金；相变；时效；调幅分解；应变强化指数
（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
