The nucleation of lattice dislocations and interface sliding at bimetal interfaces are two fundamental mechanisms of plasticity that are responsible for the mechanical responses of nanostructured materials; however, the interface-facilitated phase transformation is rarely considered owing to its relatively high energy barrier for activation. Taking the bimetal hcp/bcc interfaces with Pitch-Schrader and Burgers orientation relationships (ORs) as an illustration, we show that both non-basal dislocation nucleation and hcp-to-bcc phase transformation can be activated at the interface under external loading when the basal slip systems are effectively suppressed. The non-basal dislocation nucleation is shown to be closely related to the dynamic evolution of misfit dislocation patterns at the semicoherent interface, in which the 1/6$\left[02\overline{2}\overline{3}\right]$ pyramidal dislocation is not strictly parallel to the $\left(01\overline{1}1\right)$ stacking fault plane owing to the corrugated feature. In contrast to non-basal dislocation nucleation, phase transformation requires specific crystallographic ORs of the constituent metals under certain loading conditions, which corresponds to the process of alternate shuffle and shear deformation that involves atomistic migration. To further reveal the competition between non-basal dislocation nucleation and phase transformation, a series of twisted interface models were constructed to systematically investigate the optimal condition of the interface geometry for phase transformation. The phase transformation occurred only when the dislocation nucleation was further hindered at some specific twist angles, suggesting a strong dependence of phase transformation on the interface structure. These findings provide a foundation to the atomistic mechanism of various interface-mediated deformation and a solution to tune interface-facilitated plasticity via interface engineering.

双金属界面处晶格位错的成核和界面滑动是导致纳米结构材料机械响应的两种基本塑性机制；然而，由于其相对较高的活化能垒，很少考虑界面促进相变。以双金属 hcp/bcc 界面与 Pitch-Schrader 和 Burgers 取向关系 (ORs) 为例，我们表明，当外部加载时，可以在界面处激活非基底位错成核和 hcp-to-bcc 相变。基底滑移系统得到有效抑制。非基底位错成核与半相干界面错配位错模式的动态演化密切相关，其中 1/6$\left[02\overline{2}\overline{3}\right]$ 锥体位错并不严格平行于 $\left(01\overline{1}1\right)$由于波纹特征的堆垛层错面。与非基底位错成核相反，相变需要在某些负载条件下组成金属的特定晶体 OR，这对应于涉及原子迁移的交替洗牌和剪切变形过程。为了进一步揭示非基底位错形核与相变之间的竞争，构建了一系列扭曲界面模型，以系统地研究相变界面几何形状的最佳条件。只有当位错成核在某些特定扭曲角进一步受阻时才会发生相变，这表明相变对界面结构有很强的依赖性。