Designing high entropy alloys (HEAs) with high strength and excellent ductility has attracted extensive scientific interest. In the present work, the CALPHAD (calculation of phase diagrams) method was applied to guide the design of an (FeCoNi)₉₂Al_2.5Ti_5.5 HEA strengthened by precipitation hardening. The grain size as well as the size and volume fraction of the precipitates was tailored via a thermomechanical process to optimize the mechanical properties. The uniformly dispersed nano-precipitates are Ni₃(Al,Ti)-type precipitates with an L1₂ ordered structure presenting a fully coherent interface with the face-centered cubic (FCC) matrix. The yield strength of the alloy increases from 338.3 to 1355.9 MPa and the ultimate tensile strength increases from 759.3 to 1488.1 MPa, while the elongation maintains a reasonable value of 8.1%. The striking enhancement of strength is mainly caused by the precipitate’s hardening mechanism, which is evaluated quantitatively by various analytical models. The deformation-induced microbands and the coherent precipitates sheared by dislocations are the deformation and strengthening mechanisms contributing to the superior combination of ductility and strength in the present HEA. This investigation demonstrates that the CALPHAD method is beneficial to the design and optimization of HEAs.

设计具有高强度和出色延展性的高熵合金（HEA）引起了广泛的科学兴趣。在目前的工作中，采用CALPHAD（相图计算）方法指导通过沉淀硬化强化的（FeCoNi）₉₂ Al _2.5 Ti _5.5 HEA的设计。沉淀物的晶粒尺寸以及尺寸和体积分数是通过热机械过程定制的，以优化机械性能。均匀分散的纳米沉淀是具有L 1 _2的Ni ₃（Al，Ti）型沉淀有序结构呈现与面心立方（FCC）矩阵完全相干的界面。合金的屈服强度从338.3 MPa增加到1355.9 MPa，极限抗拉强度从759.3 MPa增加到1488.1 MPa，而伸长率则保持在8.1％的合理值。强度的显着提高主要是由沉淀物的硬化机制引起的，该机制通过各种分析模型进行了定量评估。变形引起的微带和位错剪切的相干析出物是变形和强化机制，有助于在目前的HEA中良好地结合延展性和强度。这项研究表明，CALPHAD方法有利于HEA的设计和优化。