Premartensitic State of Ti-Pd-Fe Shape Memory Alloys Studied by Electrical Resistivity, Magnetic Susceptibility and Specific Heat Measurements
Premartensitic State of Ti-Pd-Fe Shape Memory Alloys Studied by Electrical Resistivity, Magnetic Susceptibility and Specific Heat Measurements
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DOI：
10.2320/matertrans.m2009412
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发表时间：
2010-05
影响因子：
1.2
通讯作者：
M. Todai;T. Fukuda;T. Kakeshita
中科院分区：
文献类型：
--
作者：
M. Todai;T. Fukuda;T. Kakeshita
本文用电阻率、磁化率和比热等方法研究了Ti-（50-x）Pd-xFe形状记忆合金的相变行为。当x ≤ 14、16和18时，合金表现出明显的一级马氏体相变，而当x ≤ 19、20和22时，合金在4.2K以下不表现出一级马氏体相变。然而，后一种合金在低于温度Tmin的电阻率中显示出负温度系数，其随着x的增加而减小。电阻率随温度降低而增加与磁化率的降低有关。此外，在低温下的比热测量显示，后一种合金（x14 19、20和22）的电子比热系数显著大于前一种合金（x14 14、16和18）。这些结果表明，在Ti-Pd基形状记忆合金中观察到的所谓的前驱体现象是由B2相的电子结构的不稳定性引起的，在我们的小组以前研究的Ti-Ni基合金中。[doi：10.2320/matertrans.M2009412]
Transformation behavior in Ti-(50-x)Pd-xFe shape memory alloys has been investigated by electrical resistivity, magnetic susceptibility and specific heat measurements. The alloys with x ¼ 14, 16 and 18 exhibit an obvious first order martensitic transformation, but the alloys with x ¼ 19, 20 and 22 exhibit no first order transformation down to 4.2 K. However, the latter alloys show a negative temperature coefficient in electrical resistivity below a temperature Tmin, which decreases with increasing x. The increase in resistivity with decreasing temperature is associated with a decrease in magnetic susceptibility. Also, specific heat measurements at cryogenic temperatures have revealed that the electronic specific heat coefficient of the latter alloys (x ¼ 19, 20 and 22) is significantly larger than that of the former alloys (x ¼ 14, 16 and 18). These results suggest that the so-called precursor phenomena observed in Ti-Pd based shape memory alloys are caused by the instability of electronic structure of the B2-phase, as in the Ti-Ni based alloys previously studied by our group. [doi:10.2320/matertrans.M2009412]