Study On Preparation Process And Properties Of Advanced Composite Magnetostrictive Materials

Magnetostrictive material is a kind of important magnetic functional material, and hasbeen applied in many fields, such as in acoustics, sensors, electronic devices andmicro-controller. In this thesis, we studied on the preparation process and physicalproperties of several composite magnetostrictive materials which were formed withrare-earth magnetostrictive materials and ferromagnetic shape memory alloysl. Theprecursor alloys of the elastic compositie materials are prepared by arc-melting and properheat treatments. The powder bonding technology is used to fabricate the magnetostrictivecomposites which have different component ratio and internal stress. We measured andanalysized the crystal structure，magnetostriction and physical properties of the precursorsand compositesWe fabricated the composite materials of rare-earth-based magnetostrictive materialTbFe1.95and ferromagnetic shape memory alloy Mn2NiGa, Ni50Mn37Sn13and Ni50Mn37Sb13by powder bonding technology. It is found that the pressure which was arising from themagnetostriction of TbFe1.95can act on the Ni50Mn37Sn13and Ni50Mn37Sb13component toinduce the martensitic transition, the martensitic variants can also be reoriented in themagnetic field and pressure, which resulted in a larger magnetostriction. The biggest valueof component TbFe1.95:Mn2NiGa lies component ratio of6:4at the prsesure of16MPa andcomponent ratio of7:3at the preesure of18MPa, respectively. We also analysed thecontribution of TbFe1.95by using the same volume of TbFe1.95to substitute for Mn2NiGa,and figured out that30%contribution come from magnetostriction induced by thereoriented martensitic variants of Mn2NiGa at the prsesure of16MPa. The biggest value ofcomponent TbFe1.95: Ni50Mn37Sn13and TbFe1.95: Ni50Mn37Sb13both lies component ratio of7:3at the preesure of16MPa. We chose ferromagnetic shape memory alloy MM’X (M、M’for the transitional elements, X for Si、Ge、Sn) acted as new precursor alloys to study.Reseaches indicated that FeCoX, one kind of MM’X materials, FeCoGe and FeCoSn wereNi2In hexagonal phases; FeCoSi was TiNiSi orthorhombic phase, and happenedtransformation from hexagonal parent phase to orthorhombic martensite phase at1273K.Cuire temperature Tcof the parent phase and melting point decreased with increasing ofatom radiu when X was Si, Ge, Sn in proper order.