【摘要】 传统的β基Ni-Al-Fe形状记忆合金随Fe含量提高而呈铁磁性,因此可以发展为铁磁性形状记忆合金。通过金相显微分析、DSC、VSM和EDX方法,研究了Co含量x对Ni54Al25Fe21-xCox合金马氏体相变和磁性的影响。发现该合金马氏体相变温度与x成正比关系,x每增加1at%,1623K淬火时马氏体相变温度约提高30K,1373K淬火时马氏体相变温度约提高38K。淬火温度降低会显著降低Ni54Al25Fe21-xCox合金的马氏体相变温度和Curie点Tc,但随着x的提高,淬火温度对马氏体相变温度和Tc的影响程度减小。Tc随x变化的幅度不大,在Tc-x曲线上出现最大值,为256K,对应于1623K淬火的Ni54Al25Fe19Co2合金。马氏体相变温度的变化与β相的平均s+d总电子浓度变化有关,并首次提出Al含量和结构有序度两方面的变化共同影响Curie点。更多还原

【Abstract】 Ni-Al-Fe alloy with a β phase crystal structure is a conventional shape memory alloy.The alloy exhibits ferromagnetic characteristics with the increasing of Fe element concentration and thus it is a promising ferromagnetic shape memory alloy.The influence of cobalt concentration x on martensitic transformation temperature and Curie point of Ni₅₄Al₂₅Fe_21-xCo_x alloys were investigated by optical micrography,SEM,DSC and VSM and EDX analysis.It is found that the martensitic transformation temperatures of Ni₅₄Al₂₅Fe_21-xCo_x alloys are linealy increased with the increasing of Co concentration x.1% Co can increase the martensitic transition temperature by 30K for the alloys quenched from 1623K and by 38K for the alloys quenched from 1373K.Martensitic transformation temperature and Curie point decrease quickly for the alloys quenched at lower temperature.With the increasing of Co concentration x,the influence of quenching temperature on martensitic transformation temperature and Curie point is weakened.No significant influence of Co concentration on Curie point is observed.A T_c peak exists on T_c-x curves.For example,the maximum value of T_c is 256K for Ni₅₄Al₂₅Fe₁₉Co₂ alloy quenched from 1623K.Martensitic transformation temperatures of the alloys are discussed by average s+d electron concentration（e/a）,meanwhile,their Curie points are explained by the combined effects of Al content and crystal structure ordered degree of β phase at first time.更多还原