(1. 廣西大學(xué) 物理科學(xué)與工程技術(shù)學(xué)院，南寧530004；
2. 中國科學(xué)院 國際材料物理中心，沈陽110016)
摘 要: 采用晶體相場模型研究韌性單晶材料在雙軸拉伸條件下微裂紋擴(kuò)展和連通的演化過程，分析應(yīng)變、初始裂口處原子密度等因素對(duì)裂紋擴(kuò)展和分叉的影響。結(jié)果表明：初始裂口處原子密度對(duì)裂紋擴(kuò)展有明顯的影響；對(duì)于雙軸拉伸作用，當(dāng)應(yīng)變較小時(shí)，裂紋擴(kuò)展不分叉；當(dāng)應(yīng)變較大時(shí)，裂紋擴(kuò)展才能出現(xiàn)分叉。在裂紋擴(kuò)展過程中，體系能量不斷降低；當(dāng)裂紋出現(xiàn)分叉時(shí)，體系能量降低更快，這表明裂紋擴(kuò)展過程中彈性應(yīng)變能的釋放比表面能的增加要快。裂紋在擴(kuò)展過程中，在分叉處會(huì)出現(xiàn)與主裂紋斷開的孤立的微小空洞。這些微小空洞將成為新的裂紋萌生之地，它們在應(yīng)力的作用下不斷長大，連成一線，形成新的裂紋分支。同一條直線上的兩條初始裂紋在擴(kuò)展過程中，當(dāng)裂紋尖端靠近時(shí)，尖端相互吸引，裂紋相互連通。本研究所得結(jié)果與相關(guān)模擬結(jié)果和實(shí)驗(yàn)結(jié)果吻合。
關(guān)鍵字: 晶體相場模型；微裂紋擴(kuò)展；應(yīng)變；韌性材料
（1.College of Physics Science and Engineering, Guangxi University, Nanning 530004, China;
2.International Center for Materials Physics, Chinese Academy of Science, Shenyang 110016, China）
Abstract:The morphology evolution of microcrack propagation and connecting in ductile single crystal materials under the biaxial tensile deformation were simulated by the phase-field-crystal model. The effects of the factors such as the stain, the atomic density in initial crack notch on crack propagation were analyzed. The simulation results show that the atomic density in the crack notch has an effect on crack propagation. As the tensile strain exerting on the monocrystalline sample by biaxial tensile, the crack propagation cannot branch at small strain, the first-branching and second-branching occur during crack propagation when the strain is great enough. It is observed that system energy decreases over time and the energy decreases faster during crack branching. It indicates that the decrease in elastic strain energy is larger than the increase in surface energy during crack propagation. A string of isolate cavities near main cracks can be seen and these cavities will become new cracks with time lasting during crack propagation. They will continue to grow up along a line and become a new branch crack under the stress. The tips of two initial cracks on the same line would attract each other during crack propagation, once they made the connection, the two cracks would form into one. The simulation results are in agreement with other simulation results and experimental ones.
Key words: phase-field-crystal model; microcrack propagation; strain; ductile materials
