郝斯勒合金Ni-Mn-Ga中间马氏体相变研究

在马氏体相变温度(M_s)接近室温的Ni₅₂Mn₂₄Ga₂₄单晶中观察到了单纯由温度诱发的完整的热弹性中间马氏体相变.发现由于机械研磨过程中引入的内应力所导致的晶格畸变可以抑制中间马氏体相变.另外,通过对同样组分的退火和未退火的多晶样品的研究,发现中间马氏体相变与晶体的内部应力密切相关 关键词： 中间马氏体相变 2MnGa')" href="#">Ni₂MnGa

INVESTIGATION ON INTERMARTENSITIC TRANSFORMATION IN Ni-Mn-Ga ALLOY

A complete thermally induced intermartensitic transformation has already been observed in a single crystalline Ni52Mn24Ga24 sample with martensitic transformation temperature (Ms) near room temperature.As constrast with the single crystalline sample,polycrystalline samples,even those annealed ones,did not show this intermartensitic transformation.The experimental results indicates that the intermartensitic transformation can be suppressed by mechanically grinding the single crystalline sample to smaller sizes.This has been attributed to the internal stress and serious lattice distortion caused by the grinding process.The intermartensitic transformation might be suppressed by the elastic energy stored in distorted lattice.As the evidence,grinding the sample to 50μm,the martensitic transformation was even disappeared in the present measurements.Based on this point,the uncompleted intermartensitic transformation observed in the previous works can be explained.