(1. 合肥工業(yè)大學(xué) 工業(yè)與裝備技術(shù)研究院，合肥 230009；
2. 合肥工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，合肥 230009)
摘 要: 形變孿生是鎂合金的主要塑性變形方式之一，鎂合金的兩種主要孿晶為 、 孿晶，兩種常見孿晶在形貌上存在較大的差異。本文采用分子動(dòng)力學(xué)模擬與微觀組織實(shí)驗(yàn)觀察相結(jié)合的手段，研究了兩種孿晶壓縮過(guò)程的應(yīng)力應(yīng)變曲線、微觀結(jié)構(gòu)以及界面的遷移方式，對(duì)比分析兩種孿晶界面的可動(dòng)性。并且從原子運(yùn)動(dòng)以及位錯(cuò)滑移的角度，解釋兩者存在差異的原因。結(jié)果表明： 孿晶界遷移所需的應(yīng)力較 孿晶界遷移所需的應(yīng)力低，并且 孿晶界的遷移呈現(xiàn)“弓形”方式，而 孿晶界以“臺(tái)階”的方式進(jìn)行遷移。 孿晶界的遷移是B/P面相互轉(zhuǎn)變的過(guò)程，因而界面更容易大范圍、高速率地遷移；而透射電鏡(TEM)觀察和模擬結(jié)果均顯示， 孿晶界面上存在周期性的界面位錯(cuò)，阻礙了孿晶界的移動(dòng)，并且需有基面位錯(cuò)滑移至孿晶界面處堆積，為 孿晶界的遷移提供能量。
關(guān)鍵字: 鎂合金； 孿晶； 孿晶；孿晶界面可動(dòng)性；分子動(dòng)力學(xué)模擬
（1. Institute of Industry & Equipment Technology, Hefei University of Technology, Hefei 230009, China;
2. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China）
Abstract:Deformation twinning is one of the main plastic deformation modes of magnesium alloy. Two main types of twin are and . There have great differences between the morphology of two kinds of common twins. tensile twins mostly form in non-basal plane oriented grain. Once the twins have formed, it will expand rapidly, and gradually engulf the matrix. Thus the morphology features of twins are mostly lenticular. However, compression twins mostly form in basal plane oriented grain. After the formation of these twins, it is difficult to expand laterally, and the morphology features of twins are mostly narrow-flake. The combination of molecular dynamics method and microstructure experiment observation is used to establish the atomic models of two kinds of twins. In addition, the size and loading mode of the two models are consistent. This paper contrasts the mobility of two kinds of twin interfaces through analysis of stress-strain curve, microstructure and interface migration mode. And the reasons for the difference interface mobility are explained from the point of view of atomic motion and dislocation slip. The simulation and experimental results show that the stress required for twin boundary migration is lower than that for twin boundary. The migration of twin boundaries presents “bow” shape mode, while twin boundaries migrate with “step” mode. Actually, the migration of twin boundaries is the process of mutual transformation of Basal planes and Prism planes. Interestingly, the atomic arrangements of Basal plane and Prism plane are similar, thus it is easy to implement the mutual conversion process. However, it is found that there are periodic interfacial dislocations on the twin interface by TEM observation and simulation results, and the interfacial dislocations will hinder the movement of twin interface. It is also found that there are basal plane dislocation spiling up at the interface; it can provide energy for the migration of twin boundaries. Therefore, twin boundaries are easier to form large-scale and rapid migration than twin boundaries.
Key words: magnesium alloy; twin; twin; mobility of twin interfaces; molecular dynamics simulation
