Ngo Thi-Thuy Binh, Nguyen Van-Thuc, Fang Te-Hua
Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, 807, Taiwan.
Faculty of Mechanical Engineering, Ho Chi Minh City University of Technology and Education, Ho Chi Minh City, Vietnam.
J Mol Model. 2025 Mar 24;31(4):125. doi: 10.1007/s00894-025-06349-0.
This study utilizes molecular dynamics (MD) simulation to investigate polycrystalline dual-phase titanium (DP Ti) deformation behavior and phase transformation under tensile and compressive loading. The analysis focuses on the influence of hexagonal close-packed (HCP) phase fraction, strain rate, and temperature on the mechanical properties and microstructural evolution. The results indicate that increasing the HCP phase fraction enhances the elastic modulus (36.5%), yield strength, and strain hardening while maintaining acceptable ductility. The optimal mechanical performance is achieved at 75.4% HCP phase fraction. Strain rate has significantly influenced mechanical response, with higher rates promoting increased yield strength, elastic modulus, dislocation activity, and phase transformations to body-centered cubic (BCC) and amorphous phases. In contrast, raising the temperature from 300 to 900 K results in thermal softening, reduced strength, and diminished dislocation activity, alongside pronounced HCP-to-BCC phase transformation. Interphase boundaries are critical in shaping the deformation mechanisms, influencing dislocation evolution and strain hardening. During deformation, Shockley, Hirth, and other partial dislocations appear. These findings offer valuable insights into the deformation mechanisms and phase behavior of DP Ti, emphasizing its potential for applications requiring a balance between strength and ductility.
The simulations utilized the open-source software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) for modeling atomic-scale interactions. Visualization of the evolving atomic structures was performed using OVITO (Open Visualization Tool). To analyze microstructural changes, the Dislocation Extraction Algorithm (DXA) and Common Neighbor Analysis (CNA) methods were employed.
本研究利用分子动力学（MD）模拟来研究多晶双相钛（DP Ti）在拉伸和压缩载荷下的变形行为及相变。分析聚焦于六方密排（HCP）相分数、应变速率和温度对力学性能及微观结构演变的影响。结果表明，增加HCP相分数可提高弹性模量（36.5%）、屈服强度和应变硬化，同时保持可接受的延展性。在HCP相分数为75.4%时可实现最佳力学性能。应变速率对力学响应有显著影响，较高的应变速率会促进屈服强度、弹性模量、位错活性增加，并促使向体心立方（BCC）相和非晶相转变。相比之下，将温度从300 K提高到900 K会导致热软化、强度降低和位错活性减弱，同时伴随明显的HCP向BCC相变。相间边界在塑造变形机制、影响位错演变和应变硬化方面至关重要。在变形过程中，出现了肖克利位错、赫思位错和其他部分位错。这些发现为DP Ti的变形机制和相行为提供了有价值的见解，强调了其在需要强度和延展性平衡的应用中的潜力。
模拟使用开源软件LAMMPS（大规模原子/分子大规模并行模拟器）对原子尺度的相互作用进行建模。使用OVITO（开放可视化工具）对不断演变的原子结构进行可视化。为了分析微观结构变化，采用了位错提取算法（DXA）和公共邻居分析（CNA）方法。
