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采用真空热压技术在高真空和温度为523K的情况下,通过不同压力将直径平均大约为45nm的Cu纳米粉末压制成纳米结构Cu固体材料,将X射线衍射、扫描电镜与物性测试仪(PPMS)相结合,研究了低温下纳米结构Cu固体材料的比热容随温度和材料密度的变化.研究结果表明:低温比热容随着纳米结构Cu固体材料密度的降低而升高;纳米结构Cu固体材料的低温比热容大于粗晶Cu,其增加率在10K左右达到极大.基于缺陷的热振动效应,探讨了这些现象的物理机理.
Cu nanocrystalline powders with an average diameter of about 45 nm were pressed into nanostructured Cu solid materials by different pressures under the condition of high vacuum and temperature of 523K using vacuum hot pressing. X-ray diffraction, scanning electron microscopy and physical property tester (PPMS ), The change of specific heat capacity of nanostructured Cu solid materials with temperature and material density was studied at low temperature.The results show that the specific heat capacity at low temperature increases with the decrease of the density of nanostructured Cu solid materials. The low temperature The specific heat capacity is greater than that of coarse-grained Cu, and its increasing rate reaches its maximum at about 10 K. The physical mechanism of these phenomena is discussed based on the thermal shock effects of defects.