The Recarceh On The Structure, Magentism And Martinstitic Transformation Of The Ni-Based Ferromagnetic Shap Memory Alloys

This paper is based on the ferromagnetic shape memory alloy NiFeGa and NiMnSb. ByCr, Ti and Fe doping methods, respectively, the characteristics of these two kinds ofalloys,such as martensitic transformation temperature range, magnetism and otherproperties,have been adiusted.The ferromagnetic shape memory alloyNi₂FeGa with L21 structure is synthesized bythe melt-spinning technique. AC susceptibility and resistivity measurements show that themartensitic transformation temperature of the Ni₂FeGa is in the vicinity of 180K.In the alloyNi50Fe25-xCrxGa25,we find that the magnetism of this alloy is decreasing monotonously withthe substitution Cr for Fe and this alloy maintains two phase coexistence(Heusler structrureandγphase) at room temperature. The partial substitution of Ti for Fe can effectively inhibitthe formation ofγphase.In other word, The partial substitution is conducive to the formationof L21 structure.In the alloy Ni_51-xFe_xMn₃₇Sb₁₂,we find that the martensitic transformation temperature ofthis alloy increases with the substitution of Fe for Ni.And in the composition ofNi₅₀FeMn₃₇Sb₁₂, the intermediate martensitic transformation has been abserved.In the alloyNi51Mn37-xFexSb12,it is found that the martensitic transformation temperature of this alloydecreases with the substitution of Fe for Mn,which is inconsistent with existing laws.At thesame time, a new promblem that furher investgation about the martensitic transformation temperature of the ferromagnetic shape memory alloy should be done carefully has beenposed.In the alloy Ni₅₁Mn₃₇Sb_12-xFe_x,we find that the martensitic transformation temperatureof this alloy increases with the substitution of Fe for Sb.In the alloyNi₅₁Mn₃₇Sb₁₁Fe,martensitic transformation temperature is about 400K , which has layed asolid foundation for the future development of high temperature shape memory alloy.