Miyoshi Hiroshi, Kimizuka Hajime, Ishii Akio, Ogata Shigenobu
Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka, 560-8531, Japan.
Department of Materials Design Innovation Engineering, Graduate School of Engineering, Nagoya University, Aichi, 464-8603, Japan.
Sci Rep. 2021 Feb 24;11(1):4503. doi: 10.1038/s41598-021-83920-8.
Solid-state precipitation is a key heat-treatment strategy for strengthening engineering alloys. Therefore, predicting the precipitation process of localized solute-rich clusters, such as Guinier-Preston (GP) zones, is necessary. We quantitatively evaluated the critical nucleus size and nucleation barrier of GP zones in Al-Cu alloys, illustrating the precipitation preferences of single-layer (GP1) and double-layer (GP2) GP zones. Based on classical nucleation theory using an effective multi-body potential for dilute Al-Cu systems, our model predicted GP1 and GP2 precipitation sequences at various temperatures and Cu concentrations in a manner consistent with experimental observations. The crossover between formation enthalpy curves of GP1 and GP2 with increasing cluster size determines the critical conditions under which GP2 zones can nucleate without prior formation of GP1 zones. This relationship reflects competing interactions within and between clusters. The results illustrate the underlying mechanisms of competing nucleation between zones, and provide guidance for tailoring aging conditions to achieve desired mechanical properties for specific applications.
固态沉淀是强化工程合金的关键热处理策略。因此，预测局部富溶质团簇（如Guinier-Preston（GP）区）的沉淀过程是必要的。我们定量评估了Al-Cu合金中GP区的临界核尺寸和成核势垒，阐明了单层（GP1）和双层（GP2）GP区的沉淀偏好。基于经典成核理论，使用稀Al-Cu系统的有效多体势，我们的模型以与实验观察结果一致的方式预测了不同温度和Cu浓度下的GP1和GP2沉淀序列。随着团簇尺寸增加，GP1和GP2形成焓曲线之间的交叉决定了GP2区在无GP1区预先形成的情况下能够成核的临界条件。这种关系反映了团簇内部和之间的竞争相互作用。结果阐明了不同区之间竞争成核的潜在机制，并为定制时效条件以实现特定应用所需的机械性能提供了指导。
