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GH4169合金δ相的溶解行為及對變形機(jī)制的影響
發(fā)布人:上海艾荔艾金屬材料有限公司www.jshcn.cn
更新時間:2015-11-02
采用光學(xué)顯微鏡(OM)、掃描電鏡(SEM)、電子背散射衍射(EBSD)技術(shù)和透射電鏡(TEM)研究GH4169合金中δ相在高溫變形條件下的演變規(guī)律,分析δ相的溶解過程及其動力學(xué)機(jī)制,探討δ相對GH4169合金高溫變形動態(tài)再結(jié)晶機(jī)制的影響。
GH4169合金δ相的溶解行為及對變形機(jī)制的影響Dissolution behavior of δ phase and its effects on?deformation mechanism of GH4169 alloy
采用光學(xué)顯微鏡(OM)、掃描電鏡(SEM)、電子背散射衍射(EBSD)技術(shù)和透射電鏡(TEM)研究GH4169合金中δ相在高溫變形條件下的演變規(guī)律,分析δ相的溶解過程及其動力學(xué)機(jī)制,探討δ相對GH4169合金高溫變形動態(tài)再結(jié)晶機(jī)制的影響。結(jié)果表明:隨變形溫度的升高或應(yīng)變速率的降低δ相含量減少,動態(tài)再結(jié)晶晶粒尺雨和體積含量增大,δ相主要以彎曲、扭折和切斷等方式來協(xié)調(diào)塑性變形,并在界面能降低的驅(qū)動力下由針狀逐漸轉(zhuǎn)變?yōu)槎提槧钅酥燎驙睿辉诟邷刈冃螚l件下,δ相的溶解時間大大縮短,位錯、空位和曲率對δ相的溶解起到重要作用,這主要與其對溶質(zhì)原子擴(kuò)散行為的影響有關(guān),變形過程中產(chǎn)生的大量高密度位借及空位為溶質(zhì)原子提供了眾多高速率擴(kuò)散通道,促進(jìn)了δ相的溶解;δ相的存在改變了GH4169合金的動態(tài)再結(jié)晶機(jī)制,其動態(tài)再結(jié)晶機(jī)制主要有δ相誘發(fā)動態(tài)再結(jié)晶形核和非連續(xù)動態(tài)再結(jié)晶形核。
The evolution of δ phase during hot deformation of GH4169 alloy was investigated by optical microscopy (OM), electron backscattering diffractometry (EBSD), scanning and transmitting electron microscopy. The dissolution processes of δ phase and dynamic mechanisms were analyzed. The effect of δ phase on the mechanism of dynamic recrystallization (DRX) was discussed. The results show that, with increasing deformation temperature and decreasing strain rate, the content of δ phase decreases, but the grain size and volume fraction for dynamic recrystallization increase. The plastic deformation is mainly accommodated by bending, kinking and shearing of δ phase. Under the drive force of reduced interface energy, δ phase is transformed from needle to short needle and even sphere. The accelerated dissolution of δ phase can be attributed to the effect of dislocation, vacancy and curvature, which is concerned with the diffusion behavior of solute atoms. A larger amount of high-speed channels for the diffusion of solute atoms form due to the existence of massive defects, such as high density dislocations and vacancies, promoting the dissolution of δ phase. The main nucleation mechanisms of DRX are changed to be δ phase stimulated nucleation and discontinuous nucleation due to δ phase.
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