School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China.
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001, China.
Sci Rep. 2018 Jan 19;8(1):1236. doi: 10.1038/s41598-018-19449-0.
High-entropy alloys have attracted much attention due to their unique microstructures and excellent properties. Since their invention more than ten years ago, research attention has been mainly focused on the study of multicomponent alloys with equiatomic or near-equiatomic compositions. Here we propose a novel design of non-equiatomic medium-entropy alloys that contain one matrix element and several equiatomic alloying elements. To verify the utility of this new design, a series of Co-free Fe(CrNiAl) (at.%, 25 ≤ x ≤ 65) medium-entropy alloys were designed from the much-studied FeNiCrCoAl high-entropy alloy. Detailed characterization reveals that the alloys exhibit novel two-phase microstructures consisting of B2-ordered nanoprecipitates and BCC-disordered matrix. As the alloys deviate far from equiatomic composition, the structure of the nanoprecipitates transfers from a spinodal-like intertwined structure to a nanoparticle dispersed structure. Previous parametric approaches to predict phase formation rules for high-entropy alloys are unable to describe the phase separation behaviors in the studied alloys. Our findings provide a new route to design medium-entropy alloys and also demonstrate a strategy for designing nanostructured alloys from multicomponent alloy systems through simple variations in non-equiatomic compositions.
高熵合金因其独特的微观结构和优异的性能而备受关注。自十多年前发明以来，研究重点主要集中在等原子或近等原子成分的多组元合金研究上。在这里，我们提出了一种新型的非等原子中熵合金设计，其中包含一种基体元素和几种等原子合金元素。为了验证这种新设计的实用性，我们从研究较多的 FeNiCrCoAl 高熵合金中设计了一系列不含 Co 的 Fe(CrNiAl)（at.%，25≤x≤65）中熵合金。详细的表征揭示了这些合金具有新颖的两相微观结构，由 B2 有序纳米析出相和 BCC 无序基体组成。随着合金远离等原子成分，纳米析出相的结构从类似旋节分解的交织结构转变为纳米颗粒弥散结构。以前用于预测高熵合金相形成规律的参数方法无法描述所研究合金中的相分离行为。我们的发现为设计中熵合金提供了一条新途径，也展示了通过简单改变非等原子成分从多组元合金体系设计纳米结构合金的策略。
