Composition and electron concentration dependence of transformation temperature in Ni2＋x＋y Mn1-xGa1-y, Ni2＋x Mn1-x Ga alloys with first order magnetic transition were studied. For Ni2 ＋ x ＋ y Mn1- x Ga1-y alloys,...Composition and electron concentration dependence of transformation temperature in Ni2＋x＋y Mn1-xGa1-y, Ni2＋x Mn1-x Ga alloys with first order magnetic transition were studied. For Ni2 ＋ x ＋ y Mn1- x Ga1-y alloys, martensitic transformation temperature TM increases and Curie temperature Tc decreases with the increase of electron concentration e/a, they intercept at e/a = 7.68. TM and Tc decrease when continue to increase electron concentration. While for Ni2＋x Mn1-xGa alloys, they cross at e/a = 7. 635. Before their crossing, the change tendency with e/a is the same as Ni2＋x＋yMn1-xGa1-y alloys;, after their crossing, both TM and Tc increase slowly. The different relations between TM and Tc and e/a within two NiMnGa alloys show that TM and Tc depend not only on e/a, but also on composition.展开更多
Giant magnetic field induced strain （MFIS） up to 6.2% is achieved in the Ni50Mn27.5Ga22.5 single crystals with 5 M martensitic structure at room temperature. The switching magnetic field was about 2.4 kOe for the ma...Giant magnetic field induced strain （MFIS） up to 6.2% is achieved in the Ni50Mn27.5Ga22.5 single crystals with 5 M martensitic structure at room temperature. The switching magnetic field was about 2.4 kOe for the magnetostrain. A ‘magnetization jump＇ effect in the switching field applied along the initially hard direction confirms the occurrence of the large magnetostrain. The temperature dependence of the magnetostrain is investigated in lower temperature range. A linear decrease of the magnetostrain is observed with increasing temperature, but a strong decrease is monitored near the reverse martensitic transformation temperature.展开更多
文摘Composition and electron concentration dependence of transformation temperature in Ni2＋x＋y Mn1-xGa1-y, Ni2＋x Mn1-x Ga alloys with first order magnetic transition were studied. For Ni2 ＋ x ＋ y Mn1- x Ga1-y alloys, martensitic transformation temperature TM increases and Curie temperature Tc decreases with the increase of electron concentration e/a, they intercept at e/a = 7.68. TM and Tc decrease when continue to increase electron concentration. While for Ni2＋x Mn1-xGa alloys, they cross at e/a = 7. 635. Before their crossing, the change tendency with e/a is the same as Ni2＋x＋yMn1-xGa1-y alloys;, after their crossing, both TM and Tc increase slowly. The different relations between TM and Tc and e/a within two NiMnGa alloys show that TM and Tc depend not only on e/a, but also on composition.
基金Supported by the National Natural Science Foundation of China under Grant No 50271002, and the New Century Programme for Excellent Talents of the Ministry of Education of China under Grant No 04-0165.
文摘Giant magnetic field induced strain （MFIS） up to 6.2% is achieved in the Ni50Mn27.5Ga22.5 single crystals with 5 M martensitic structure at room temperature. The switching magnetic field was about 2.4 kOe for the magnetostrain. A ‘magnetization jump＇ effect in the switching field applied along the initially hard direction confirms the occurrence of the large magnetostrain. The temperature dependence of the magnetostrain is investigated in lower temperature range. A linear decrease of the magnetostrain is observed with increasing temperature, but a strong decrease is monitored near the reverse martensitic transformation temperature.
