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The effect of neodymium (Nd) additions from 0 to 0.2 wt.% on microstructure, mechanical properties at room and high temperature, as well as corrosion resistance of 2A70 alloy were studied by optical microscopy (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM) in this paper. The results show that appropriate addition of Nd (0.15 wt.%) refines the size and enhances the density of the aging precipitates S′ phase, which lead to the increasing of mechanical properties at room and elevated temperatures. The newly formed Al8Cu4Nd compound, dispersed along grain boundary, which hinders the movement of grain boundaries at elevated temperature and improves the high temperature performance of 2A70 alloy. Compared with traditional 2A70 alloy, the intergranular corrosion of the peak-aged alloy with 0.15 wt.% Nd has also been effectively enhanced. [ABSTRACT FROM AUTHOR]

The strength-ductility trade-off has always been a difficult issue in the development of highperformance structural materials. In this work, a new non-equiatomic Fe 37.5 Ni 30 Co 22.5 Al 5 Ti 5 (at%) high entropy alloy (HEA) was developed, which shows both excellent strength and ductility. The yield strength of the aged HEA reached 1094 MPa, which is more than twice that of the solid-solution HEA, while the ultimate tensile strength was 1275 MPa, and the elongation to failure was ∼38%. The high yield strength resulted from precipitation strengthening provided by a high number density of L1 2 -Ni 3 (Al, Ti) nanoprecipitates. Both a small grain size and the nanoprecipitates can induce high local stresses, enhancing the phase transformation from face-centered cubic (FCC) to martensite that occurs in this HEA, and which can lead to the good ductility. As much as possible to keep strength-ductility through the coupling between precipitation strengthening and TRIP effect is a suitable strategy to overcome the strength and ductility trade-off. • The yield strength of the aged HEA is more than twice that of the solid-solution HEA with the elongation loss of only ∼19 %. • Under the coupling between precipitation strengthening and TRIP effect, the AG HEA shows excellent mechanical properties. • The nanoprecipitates change the SFE of the matrix and promote the occurrence of phase transformation to some extent. [ABSTRACT FROM AUTHOR]