高纯铝再结晶晶界面的择尤取向

Preferred orientation of grain boundary plane in recrystallized high purity aluminum

相比于传统的晶体择尤取向（晶体织构,简称织构）,晶界面择尤取向是一个新的科学问题.系统地研究晶界面择尤取向的形成规律和演化机制对合理调控显微组织结构以显著改善材料的各种使用性能具有非常重要的科学意义和应用价值.本文利用基于体视学原理和电子背散射衍射技术的晶界特征分布五参数表征分析方法,研究了冷轧变形高纯铝（99.99%）再结晶晶界面的择尤取向问题.结果表明,在再结晶及晶粒长大过程中,晶界面择尤取向由最初的{2 2 3}晶面转变为{1 1 1}晶面,最后取向在{1 0 0}晶面上.分析指出,冷轧变形高纯铝再结晶组织中,小角度晶界（取向差介于2°~15°）是其晶界构成的主体部分;在晶粒长大过程中,晶体织构由{1 1 0}〈1 1 2〉黄铜织构为主转变为以{0 1 1}〈1 0 0〉高斯织构和{0 2 3}〈1 0 0〉织构共存为主,受晶面能和晶体织构的影响,小角度晶界一般择尤取向于可形成能量较低的倾侧型小角度晶界所对应的晶面上.这是导致高纯铝再结晶晶界面择尤取向随晶粒长大而发生上述规律性变化的主要原因.

Compared with the research of preferred orientation of crystals （crystallographic texture） which started nearly a century ago, preferred orientation of grain boundary plane in polycrystalline materials is a lately proposed research direction with the development of five parameter analysis which is based on electron backscatter diffraction and stereological method. Systematic investigations into the preferred orientation of grain boundary plane and in-depth understanding on their evolution natures will be important to the manipulation of the microstructures of desired properties. In current paper, high purity aluminum （99.99 wt%） samples were cold rolled with 85% thickness reduction followed by a recrystallization annealing at 330~C for 15-60 minutes and then the grain boundary plane orientations were studied. The results indicate there indeed exist preferred orientations of grain boundary planes in the recrystallized microstructure and the preferred orientation evolves sequentially from {2 2 3} to { 1 1 1 } and { 1 0 0} planes during grain growth. Further discussion points out the recrystallization of high purity aluminum after cold rolling could be a so-called continuous recrystallization which involves sub-grain coalescence and sub-grain growing, and low angle grain boundary （mis- orientation angles ranging from 2° to 15°） constitutes the main part of the entire grain boundaries in the recrystailized microstructure. During grain growth, the crystallographic texture evolves from {1 1 0}（1 1 2） （Brass） to {0 1 1}（1 0 0） （Goss） and {0 2 3}（1 0 0）coexisted, and low angle grain boundary planes usually orient on the exact position of low energy tilt boundaries due to the effects of crystallographic texture and crystallographic plane energy. This is the reason for the regular evolution of the preferred orientation of grain boundary planes as observed.