Al-Zn-Mg-Cu合金銑削表面變形層的微觀組織和織構(gòu)

Al-Zn-Mg-Cu合金銑削表面變形層的微觀組織和織構(gòu)Microstructure and Texture in Surface Deformation Layer of Al-Zn-Mg-Cu Alloy Processed by Milling

利用透射電鏡（TEM）技術(shù)以及配套的旋進(jìn)電子衍射（PED）技術(shù)對銑削Al-Zn-Mg-Cu合金表面變形層的微觀組織和織構(gòu)進(jìn)行研究。結(jié)果表明：表面變形層是由最表層的等軸納米晶/超細(xì)晶層和亞表層的層狀納米晶/超細(xì)晶層組成，晶粒周圍分布大量的粗大晶界析出相（GBPs）；最表層再結(jié)晶的納米晶/超細(xì)晶的存在說明除了位錯(cuò)運(yùn)動(dòng)，動(dòng)態(tài)再結(jié)晶也在晶粒細(xì)化過程中發(fā)揮作用；與原始粗晶相比，加工表面變形層內(nèi)GBPs和晶內(nèi)析出相（GIPs）尺寸和密度明顯的不同是由于熱機(jī)械作用誘發(fā)析出相重新分布；表面變形層的織構(gòu)類型為由近銅型織構(gòu){112}<111>、旋轉(zhuǎn)立方織構(gòu){001}<110>和F型織構(gòu){111}<112>組成的混合型織構(gòu)，銑削加工過程引入的表面劇烈剪切變形是上述織構(gòu)形成的主要原因。

The microstructural and crystallographic features of the surface deformation layer in Al-Zn-Mg-Cu alloy induced by milling were investigated by means of transmission electron microscopy (TEM) and precession electron diffraction (PED) assisted nanoscale orientation mapping. The result shows that the surface deformation layer is composed by the top surface of equiaxed nanograins/ultrafine grains and the subsurface of lamellar nanograins/ultrafine grains surrounded by coarse grain boundary precipitates (GBPs). The recrystallized nanograins/ultrafine grains in the deformation layer show direct evidence that dynamic recrystallization plays an important role in grain refining process. The GBPs and grain interior precipitates (GIPs) show a great difference in size and density with the matrix due to the thermally and mechanically induced precipitate redistribution. The crystallographic texture of the surface deformation layer is proved to be a mixture of approximate copper{112}<111>, rotated cube{001}<110> and F {111}<112>. The severe shear deformation of the surface induced by milling is responsible for the texture evolution.

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