不同晶粒尺寸Ni－P合金纳米晶体的界面过剩体积研究

用非晶晶化法制备尺寸为１３－１０７ｎｍ的Ｎｉ－Ｐ合金纳米晶体．利用正电子湮没技术研究了尺寸不同的纳米晶体中界面缺陷类型及其分布，发现单位体积界面的缺陷含量随晶粒减小而降低．由精细的密度测量和界面结构特征估算纳米晶体样品中的界面体积过剩率随晶粒减小而显著降低，发生致密化现象，这一结果与正电子湮没实验及其它性能测试结果十分吻合．

INTERFACIAL EXCESS VOLUME IN NANOCRYSTALLINE Ni-P ALLOYS WITH DIFFERENT GRAIN SIZES

Nanocrystalline Ni-P alloy samples with grain sizes ranging from 13 nm to 107 nm have been prepared by the crystallization method. A positron annihilation spectroscopy technique was used to investigate the interfacial defects in these nanocrystalline samples.It was found that with a decrease of grain size,the excess volume in a unit volume of interfaces is reduced. By means of accurate density measurement and structural characteristic analyses of the nanocrystalline samples, the interfacial excess volume in the sample is found to be decreasing with reduction of grain size,i.e. a densification of interfaces.This result is in a good agreement with those from the positron annihilation experiments and from other property measurements.