The effect of the relative contents of Al and Ti on the equilibrium phase formation in a novel Ni₅₁Co₁₈Fe₅Cr₁₀Al_16-XTi_X high entropy superalloy (HESA) system was analysed using Thermo-Calc software (TCHEA-3 database). The proposed HESAs showed a broad γ+γ′ equilibrium phase field over an extended temperature range (from 660 ^°C to a γ′-dissolution temperature >1184 ^°C) without the presence of brittle intermetallic phases. The effect of Al/Ti ratio on the microstructure, mechanical properties and precipitation strengthening of the HESAs was determined. The proposed alloys showed a high volume fraction (∼60%) of a (Ni, Co)₃(Al, Ti)-type ordered (γ′) phase in a disordered face-centered cubic matrix phase (γ). The microstructure and the thermal properties of the HESAs showed excellent correlation to the theoretical thermodynamic predictions. A lower Al/Ti ratio improved the mechanical properties of the HESA system due to the high lattice misfit between the γ and γ′ phases. The homogenised and aged Ni₅₁Co₁₈Fe₅Cr₁₀Al₈Ti₈ HESA exhibited a γ′-volume fraction of 63%, γ′-dissolution temperature of 1200 ^°C and yield strengths of 1056 MPa and 852 MPa at room-temperature and 800 ^°C, respectively. The present work shows the potential to design Al–Co–Cr–Fe–Ni–Ti HESAs with a high volume fraction of γ′-phase and excellent mechanical properties.

使用_{Thermo -} Calc软件_（ TCHEA - _{3 _} _ _ _{_}数据库）。所提出的 HESA 在扩展的温度范围（从 660  ^° C 到 γ'-溶解温度 >1184  ^° C）显示出宽的 γ+γ' 平衡相场，而没有脆性金属间相的存在。测定了Al/Ti比对HESAs的显微组织、力学性能和析出强化的影响。所提出的合金显示出高体积分数（~60％）的（Ni，Co）₃（Al，Ti）型有序（γ'）相在无序的面心立方矩阵相（γ）中。HESA的微观结构和热性能与理论热力学预测显示出极好的相关性。由于 γ 和 γ' 相之间的高晶格失配，较低的 Al/Ti 比改善了 HESA 系统的机械性能。均质和时效的Ni ₅₁ Co ₁₈ Fe ₅ Cr ₁₀ Al ₈ Ti ₈ HESA在室温下的γ'-体积分数为63%，γ'-溶解温度为1200  ^° C，屈服强度分别为1056 MPa和852 MPa和 800  ^°C，分别。目前的工作显示了设计具有高 γ′ 相体积分数和优异机械性能的 Al-Co-Cr-Fe-Ni-Ti HESA 的潜力。