Study On Physical And Mechanical Properties Of The Manganese-based Shape Memory Alloy

Mn-based magnetic shape memory alloys are antiferromagnetic alloys with multi-functional characteristics. Compared with the ferromagnetic materials, their functional and practical applications have not yet been fully developed. Therefore, it is important for studying the physical and mechanical properties of these materials.In this paper, the physical and mechanical properties of medium manganese MnFe alloys were studied by means of X-ray diffraction (XRD), photomicrograph, thermal expansion method, differential scanning calorimetry (DSC), resistance strain gauge method, and compression test. At the same time, the mechanical property in antiferromagnetic MnFe (Cu) alloys and the effect of Cobalt content on the microstructure and property of magnetic-field-induced strain (MFIS) in MnFe alloy were also studied. The results as follows:(1) Mn65Fe35alloy and Mn60Fe40alloy were y phase after the solution treated and water quenched. And there was paramagnetic to antiferromagnetic transition in the alloy when they were cooled from the high temperature to room temperature. Therefore, the microstructure was antiferromagnetic austenite in the room temperature. MFIS can be obtained in polycrystalline MnFe alloys in the external magnetic field, which was increased with the increase of the applied magnetic field intensity, decreased with the decrease of the applied magnetic field intensity and finally completed the entire recovery process. And the alloys were all possessed of pseudoelasticity under the compression test in the room temperature.(2) The samples that are Mn51Fe49alloy, Mn78F17Cu5alloy, Mn80Fe15Cu5alloy and Mn85Fe10Cu5alloy used in this test were possessed of pseudoelasticity. The pseudoelasiticity of Mn51Fe49, Mn78Fe17Cu5and MngoFe15Cu5alloys increased with the target load increasing. And in Mn85Fe10Cu5alloy, when the loading cycles were fewer, the pseudoelasticity increased with the increase of loading cycles. When the loading cycles continued to increase, the pseudoelasticity would drop.(3) Mn70Fe30-xCox (x=0,2,4) alloys were single phase y in the room temperature after the solution treated and water quenched. With the increase of Co content, the Neel temperatures of alloys decreased, which was all higher than the room temperature, that’s to say, the alloys exhibited antiferromagnetic austenite microstructure in the room temperature after quenching from high temperature. Alloys possessed much larger MFIS with the increase of Co content, and taking as an example, when magnetic field strength was1.1T, the MFIS was at its maximum,6×10-5.