【摘要】 用自动真空倒扭摆测量了纯镧在80～700K的内耗和相对切变模量,观测到六个内耗峰。升温过程的H₁峰和降温过程的C₂峰是由镧的FCC-dHCP结构相变引起的,H₂和C₁ 峰则可能与这种相变还存在着预转变有关。用内耗方法确定了相变点γ_s、γ_?、β_s、β（?）分别为540、650、487和425K。H₃、H₄、H₅、H₆四个内耗峰用2.21Hz的频率测得的峰温分别为366、272、207.2、和119K,其中H₅峰具有弛豫型内耗特征。还测量了纯镧在77～700K范围的磁化率,观测到1/X T线段在FCC-dHCP相变温度出现斜率转折。更多还原

【Abstract】 The lanthanum wires of 99.8% purity with 1-2mm diameter were used in the investigation. The internal friction Q^-1 and relative shear modulus F² were measured in an automatic inverted torsion pendulum. The magnetic susceptibility X was also determined The experimental results are as follows: 1 Q^-1 of annealed La as a function of temperature above 400K show two peaks Thermal hysteresis, frequency independence of the peak temperature, heating （or cooling） rate and frequency dependences of the peak hight are features of Q^-1 caused by phase transition. These features have been observed. Certain correlation between the two peaks has also been observed It is suggested that a pretransformation might be incluled in the phase transition of La A dislocation mode of the transformation FCC（?）dHCP was discussed. 2. Q^-1 and F² vs. temperature show a complex spectrum over the range of 80- 400K. The spectrum depends upon the thermal cycles.With 2.2 Hz frequency the internal friction peaks appear at 366, 272, 207 and 119K respectively The peak at 207K may be associated with a relaxation process with an activation enthalpy 0.35eV. 3 The temperature dependence of reciprocal magnetic susceptibility 1/X follows the Curie-Weis law in the different temperature ranges and may be represenied by a broken line. The break point at 530 K should correspond to the phase transition from dHCP to FCC.更多还原