析出及生长动力学
(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 采用透射电子显微镜(TEM)研究了Ag在时效过程中对析出相形核及生长的影响， 并发展了析出相生长的动力学模型。 模型指出： 在时效过程中， Al-Cu-Mg合金中析出的θ′相通过台阶机制生长而发生共格失稳， 转化成球状的θ相而导致强度显著下降； Al-Cu-Mg-Ag合金中的Ω相由于在界面被Mg和Ag原子覆盖， 降低了Ω相的生长速度； 同时， Mg和Ag原子在析出相界面的存在降低了晶格畸变能， 使得Ω相能够保持片状而不发生共格失稳， 高温下具有较高的强度。力学实验及显微组织分析表明： 分别均匀分布在铝基体（001）和（111）面上共存的θ′和Ω（成分为Al2Cu）沉淀相对含Ag合金起着强化作用。
关键字: Al-Cu-Mg-Ag合金； 力学性能； 显微组织； 台阶机制
during aging
（State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: The effects of Ag on precipitation and growth of the precipitates in Al-Cu-Mg alloy during aging were studied by transimsson electron microscopy(TEM), and the dynamic model about the growth of precipitates was developed. The model indicates that θ′ phase precipitated from Al-Cu-Mg alloy grows through ledge mechanism and loses coherence. The Ω phase grows very slow due to the Mg and Ag layer exist on the interface between the precipitates and the matrix. At the same time, the existence of Mg and Ag layer decreases the lattice aberrant energy and make the Ω phase keep coherent. Thus, the Al-Cu-Mg-Ag alloy has high mechanical properties under high temperature. The mechanical testing and microstructural analysis results indicate that the alloy with Ag is strengthened by a homogeneous distribution of coexistent θ′, and Ω precipitates (Al2Cu) on the (001) and (111) planes of matrix, respectively.
Key words: Al-Cu-Mg-Ag alloy; mechanical property; microstructure; ledge mechanism
