Cu-3.2Ni-0.75Si合金时效早期相变规律及强化机理

Transformation and strengthening of early stage of aging in Cu-3.2Ni-0.75Si alloy

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 45 0℃时效 4h左右富溶质区内形成Ni2 Si相 ,形成的Ni2 Si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 45 0℃时效 2h的调幅组织的强化效应为 34 2MPa,45 0℃时效 4h形成的Ni2 Si相的强化效应为 40 5MPa ,该数值与实验结果非常吻合。

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 Ni 2Si 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 2 h is calculated to be 342 MPa by using dislocation theory, and that of the Ni 2Si phase precipitated in aging at 450 ℃ for 4 h is about 405 MPa, which are quite consistent with the experimental data.