Abstract
Brittleness and low working temperature are two key factors that restrict the application of Ni-Mn-Sn alloys. Element doping is an effective means to improve performance of materials. In present paper, martensitic transformation (MT) and mechanical properties of Ni48Mn39Sn13−xTbx (x = 0, 0.5, 1, 2, and 5 at.%) alloys are investigated. It is found that the Tb addition refines significantly the grains and causes the formation of a Tb-rich phase. All the samples undergo the martensitic transformation from parent phase to martensite. And the martensitic transformation characteristic temperatures increase remarkably from −60.7 °C for x = 0 to 364.1 °C for x = 5. The appropriate amount of Tb addition in Ni48Mn39Sn13−xTbx (x = 0, 0.5, 1, 2, and 5 at.%) alloys significantly enhances the compressive strength and improves the ductility, which can be ascribed to the grain refinement. The compressive stress of 571.8 MPa and strain 22.0% are obtained in the Ni48Mn39Sn11Tb2 alloy. Then the mechanical properties decrease with the further increased Tb content. Simultaneous improving of martensitic transformation temperature and mechanical properties in Ni-Mn-Sn magnetic alloy are achieved by Tb doping.
Highlights
Compared to traditional shape memory alloys (SMAs), ferromagnetic shape memory alloys (FSMAs) can produce force and deformations by applying a magnetic field
The magnetocaloric effect (MCE) is a magneto-thermodynamic phenomenon in which a temperature change of a suitable material is caused by exposing the material to a changing magnetic field [13,16,17,18,19,20,21,22]
We anticipate that Tb addition in Ni-Mn-Sn alloys will have an amazing effect on the mechanical properties and martensitic transformation behavior
Summary
Compared to traditional shape memory alloys (SMAs), ferromagnetic shape memory alloys (FSMAs) can produce force and deformations by applying a magnetic field. As a typical magneto-structurally coupled ferromagnetic shape memory alloy (FSMAs), Ni-Mn-Sn alloys undergo a magnetic-field-induced reverse martensitic transformation from antiferromagnetic martensite to ferromagnetic austenite. Some researchers have reported that rare earth element addition could improve the martensitic transformation temperature. It can be anticipated that doping a suitable rare earth element into Ni-Mn-Sn FSMAs may simultaneously tune the mechanical properties and martensitic transformation temperature. There is still a lack of knowledge and information about the rare earth element Tb addition in Ni-Mn-Sn FSMAs. In this paper, we anticipate that Tb addition in Ni-Mn-Sn alloys will have an amazing effect on the mechanical properties and martensitic transformation behavior. The compressive stress increases from 74.3 MPa to 571.8 MPa and the compressive strain increase form 9.2% to 22.0% with increasing Tb content from 0 at.% to 2 at.%
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