Ultrasonic study of the temperature and hydrostatic‐pressure dependences of the elastic properties of polycrystalline cementite (Fe3C)
Ultrasonic study of the temperature and hydrostatic‐pressure dependences of the elastic properties of polycrystalline cementite (Fe3C)
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多晶渗碳体 (Fe3C) 弹性性能的温度和静水压力依赖性的超声研究
DOI：
10.1002/pssa.200306613
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
M. Acet
中科院分区：
文献类型：
--
作者：
S. Dodd;G. Saunders;M. Cankurtaran;B. James;M. Acet
超声波速度的脉冲回波重叠测量已用于确定多晶渗碳体 (Fe3C) 的弹性刚度模量对 75-295 K 范围内的温度和室温下高达 0.1 GPa 的静水压力的依赖性。随着温度的降低，纵向刚度 (CL) 和绝热体积模量 (BS) 会变硬，而剪切刚度 (μ) 和杨氏模量 (E) 会软化。超声波速度随压力近似线性增加，纵向速度比剪切模式的速度陡峭得多。在 295 K 时获得的渗碳体静水压导数 (∂CL/∂P)P=0、(∂μ/∂P)P=0 和 (∂BS/∂P)P=0 的值分别为 7.9 ± 1.7、1.4 ± 0.1 和 6.1 ± 1.7：区域中心声子在压力下变硬。渗碳体的纵向（γL）、剪切（γS）和平均（γel）声模Gruneisen参数均为正值； γS 明显小于 γL，表明剪切声波模态的非谐性小于纵模态。
Pulse-echo-overlap measurements of ultrasonic wave velocity have been used to determine the dependences of the elastic stiffness moduli of polycrystalline cementite (Fe3C) on temperature in the range 75–295 K and hydrostatic pressure up to 0.1 GPa at room temperature. The longitudinal stiffness (CL) and adiabatic bulk modulus (BS) stiffen, while the shear stiffness (μ) and Young's modulus (E) soften with decreasing temperature. The ultrasonic velocities increase approximately linearly with pressure, much more steeply for the longitudinal than the shear mode. The values obtained at 295 K for the hydrostatic-pressure derivatives (∂CL/∂P)P=0, (∂μ/∂P)P=0 and (∂BS/∂P)P=0 of cementite are 7.9 ± 1.7, 1.4 ± 0.1 and 6.1 ± 1.7, respectively: the zone-centre acoustic phonons stiffen under pressure. The longitudinal (γL), shear (γS) and mean (γel) acoustic-mode Gruneisen parameters of cementite are positive; γS is markedly smaller than γL indicating that the shear acoustic modes are less anharmonic than the longitudinal modes.