摘要
通过研究铁磁性金属间化合物Ni2 +xMn1-xGa(x =- 0 1,0 ,0 0 8,0 13,0 18,0 2 )和Ni2 -xMn1+x/ 2 Ga1+x/ 2(x =- 0 1,0 ,0 0 4,0 0 6 ,0 1)两个系列多晶样品的交流磁化率随温度的变化行为 ,得到了化合物在不同组分下的马氏体相变温度TM 和居里温度TC.发现随着Ni成分的增加 ,前者的马氏体相变温度Tm 增加 ,而居里温度TC降低 ,后者的马氏体相变温度Tm 和居里温度TC 均是先增大后减小 .报道了Tm 在室温附近的单晶样品Ni52 Mn2 4Ga2 4 的磁场增强双向形状记忆效应 .发现伴随着马氏体相变 ,样品在 [0 0 1]方向可产生 1 2 %的收缩 .如果在该方向施加 1 2T的偏磁场可以使该应变值增大到 4 0 % .而垂直于 [0 0 1]方向施加 1 2T的偏磁场时 ,在 [0 0 1]方向产生1 6 %的膨胀 .阐明了产生大应变的原因并非相界移动 ,而是单晶的杂散内应力小和外加磁场通过孪晶界移动使马氏体变体重组的共同结果 .
The martensitic phase transformation temperature, T-m and the Curie temperature, T-C, of polycrystalline samples Ni2+xMn1-xGa(x = -0.1,0,0.08,0.13,0.18,0.2) and Ni2-xMn1+x/2Ga1+x/2(x = -0.1,0,0.04,0.06,0.1) have been investigated by measuring the temperature dependence of alternating-current susceptibility. It was found that, with the increase of Ni content, T-C decreases and T-m increases for Ni2+xMn1-xGa, and both T-C and T-m increase first and decrease afterwards for Ni2-xMn1+x/2Ga1+x/2 Stress-free and two-way thermoelastic shape memory, with 1.2% strain, has been found in single crystal Ni52Mn24Ga24 The deformation can be enhanced more than three times, up to 4.0% shrinkage with a bias field 1.2T applied along the measurement direction. The origin of large recoverable strain should be attributed to the low level of internal stress and the field-induced rearrangement of martensitic variants through twin boundary motion rather than the phase boundary motion.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2001年第2期233-238,共6页
Acta Physica Sinica
