Tuning deformation mechanisms is imperative to overcome the well-known strength-ductility paradigm. Twinning-induced plasticity (TWIP), transformation-induced plasticity (TRIP) and precipitate hardening have been investigated separately and have been altered to achieve exceptional strength or ductility in several alloy systems. In this study, we use a novel solid-state alloying method—friction stir alloying (FSA)—to tune the microstructure, and a composition of a TWIP high-entropy alloy by adding Ti, and thus activating site-specific deformation mechanisms that occur concomitantly in a single alloy. During the FSA process, grains of the as-cast face-centered cubic matrix were refined by high-temperature severe plastic deformation and, subsequently, a new alloy composition was obtained by dissolving Ti into the matrix. After annealing the FSA specimen at 900 °C, hard Ni–Ti rich precipitates formed to strengthen the alloy. An additional result was a Ni-depleted region in the vicinity of newly-formed precipitates. The reduction in Ni locally reduced the stacking fault energy, thus inducing TRIP-based deformation while the remaining matrix still deformed as a result of TWIP. Our current approach presents a novel microstructural architecture to design alloys, an approach that combines and optimizes local compositions such that multiple deformation mechanisms can be activated to enhance engineering properties.

为了克服众所周知的强度-延性范式，必须调整变形机制。孪生诱导的可塑性（TWIP），相变诱导的可塑性（TRIP）和沉淀硬化已分别进行了研究，并进行了更改，以在几种合金体系中获得出色的强度或延性。在这项研究中，我们使用一种新型的固态合金化方法-摩擦搅拌合金（FSA）来调整微观结构，并通过添加Ti来调整TWIP高熵合金的成分，从而激活发生的特定位置的变形机制同时使用一种合金。在FSA过程中，铸态的面心立方基体的晶粒通过高温剧烈塑性变形而细化，随后，通过将Ti溶解在基体中获得了新的合金成分。在FSA试样在900°C退火之后，形成坚硬的富含Ni-Ti的沉淀以增强合金。另一个结果是在新形成的沉淀物附近有一个镍耗尽的区域。Ni的减少会局部降低堆垛层错能，从而引起基于TRIP的变形，而其余基体仍由于TWIP而变形。我们当前的方法提出了一种新颖的显微组织结构来设计合金，这种方法结合并优化了局部成分，从而可以激活多种变形机制以增强工程性能。从而导致基于TRIP的变形，而其余的矩阵仍由于TWIP而变形。我们当前的方法提出了一种新颖的显微组织结构来设计合金，这种方法结合并优化了局部成分，从而可以激活多种变形机制以增强工程性能。从而导致基于TRIP的变形，而其余的矩阵仍由于TWIP而变形。我们当前的方法提出了一种新颖的显微组织结构来设计合金，这种方法结合并优化了局部成分，从而可以激活多种变形机制以增强工程性能。