Wang Kui, Jiang Haiyan, Wang Qudong, Wang Yingxin
National Engineering Research Center of Light Alloys, Net Forming, Shanghai Jiao Tong University, Shanghai 200240, China.
State Key Laboratory of Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai 200240, China.
Materials (Basel). 2023 Jan 31;16(3):1214. doi: 10.3390/ma16031214.
In this study, TiCN nanoparticles (NPs) are shown to induce a remarkable grain refinement of aluminum at various cooling rates. The grain refinement mechanisms are systematically investigated by microstructure observation, edge-to-edge matching (E2EM) model prediction, and first-principles calculations. The experimental results suggest that as the cooling rates increase from 10 K/s to 70 K/s, a transition from intergranular to intragranular distribution of NPs occurs and the Al/TiCN interface varies from incoherent to coherent. Based on the E2EM analysis combined with first-principles calculation, it is found that TiCN can act as a potent nucleant for the heterogeneous nucleation of α-Al. By analyzing the NP effects on the nucleation and growth of α-Al, the grain growth restriction and nucleation promotion mechanisms are proposed to elucidate the refinement phenomena at low and high cooling conditions, respectively.
在本研究中，TiCN纳米颗粒（NPs）在不同冷却速率下均能显著细化铝晶粒。通过微观结构观察、边到边匹配（E2EM）模型预测和第一性原理计算，系统地研究了晶粒细化机制。实验结果表明，随着冷却速率从10 K/s增加到70 K/s，NPs的分布从晶间转变为晶内，且Al/TiCN界面从不相干变为相干。基于E2EM分析并结合第一性原理计算，发现TiCN可作为α-Al异质形核的有效形核剂。通过分析NPs对α-Al形核和生长的影响，分别提出了晶粒生长限制机制和成核促进机制，以阐明低冷却条件和高冷却条件下的细化现象。
