析出及生長動力學(xué)
(中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 采用透射電子顯微鏡(TEM)研究了Ag在時效過程中對析出相形核及生長的影響， 并發(fā)展了析出相生長的動力學(xué)模型。 模型指出： 在時效過程中， Al-Cu-Mg合金中析出的θ′相通過臺階機制生長而發(fā)生共格失穩(wěn)， 轉(zhuǎn)化成球狀的θ相而導(dǎo)致強度顯著下降； Al-Cu-Mg-Ag合金中的Ω相由于在界面被Mg和Ag原子覆蓋， 降低了Ω相的生長速度； 同時， Mg和Ag原子在析出相界面的存在降低了晶格畸變能， 使得Ω相能夠保持片狀而不發(fā)生共格失穩(wěn)， 高溫下具有較高的強度。力學(xué)實驗及顯微組織分析表明： 分別均勻分布在鋁基體（001）和（111）面上共存的θ′和Ω（成分為Al2Cu）沉淀相對含Ag合金起著強化作用。
關(guān)鍵字: Al-Cu-Mg-Ag合金； 力學(xué)性能； 顯微組織； 臺階機制
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
