Martensite Transformation and Mechanical Properties of Polycrystalline Co-Ni-Al Alloys with Gd Doping

Abstract

In order to improve the mechanical properties and phase transition temperature, the influence of Gd doping on the microstructure, phase transition temperature and mechanical properties of Co35Ni32Al33 alloy was investigated. The results show that the γ+β phase was observed in the microstructure of the sample with less Gd doping and the γ phase+martensite was found with more Gd content. The phase transition temperature apparently increases with Gd doping and the phase transition temperature goes over room temperature when the Gd is 3 at.% or more. With increasing Gd doping, more γ phase appears in the sample which results in decrease in hardness. The compressive strength decreases from 2274 to 1630 MPa and the ductility increase from 4.2 to 12.9% with increasing Gd content.

Tunable Martensitic Transformation and Magnetic Properties of Sm-Doped NiMnSn Ferromagnetic Shape Memory Alloys

“…With a small amount of Sm doping (x = 1), the T t increases, with a range of 62 to 69 K, i.e., the A s , A f , M s and M f are increased by 69, 62, 64 and 65 K, respectively. An increase in the T t has already been reported in FMSMAs by Gd (rare element substitution) [36][37][38]. With the further increase, the M t shows an overall increasing tendency.…”

“…With the further increase, the Mt shows an overall increasing tendency. The first-order nature of the transformation is evident by the presence of thermal hysteresis among the heating and cooling processes [37]. The characteristic MT temperatures are the austenite start temperature A s , austenite finish temperature A f , martensite start temperature M s and martensite finish temperature M f .…”

Microstructure and Magnetic Field-Induced Strain of a Ni-Mn-Ga-Co-Gd High-Entropy Alloy

“…For FSMAs, the martensitic transformation is extremely sensitive to the change in alloy composition. This is because the valence electron concentration (Re/a), in the alloy, is linearly correlated with the martensitic transformation temperature [ 30 , 31 ]. In the present study, and for the high-entropy design of alloys, the relation between Ms and Re/a can be determined by using Equation (1) [ 32 ]: where S ↑ and S ↓ are the spin-up and spin-down electrons, respectively.…”