在脉冲电沉积过程中, 采用超声波搅拌制备了厚度约为90μm的金属镍镀层. XRD和TEM对不同超声波强度下制备的镀层的分析表明, 镍镀层的晶粒尺寸随着超声波强度的变化而变化. 在固定脉冲电解参数导通时间(ton)和关断时间(toff)分别为0.2和0.8 ms,平均电流密度为10 A/dm2、镀液pH值为4.0、温度为50℃的条件下,当施加的超声波强度由0 W增至50 W时, 镀层平均晶粒尺寸从45 nm减至24 nm; 但当超声波强度增至70 W时,镀层的平均晶粒尺寸增至38 nm. 显微硬度测试结果表明, 平均粒径为24 nm的镍镀层的HV高达760.。
We present ab initio calculations of the thermal properties of hcp metals Zr. We show that the thermal properties such as thermal expansions and heat capacities in hcp metal can be calculated precisely within the quasiharmonic approximation, by using phonon dispersions from density-functional perturbation theory, and the pseudopotential plane-wave method. Our results for the thermal properties are in good agreement with available experimental data in a wide range of temperatures.
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