Sasaki Yo, Shimada Haruhiko, Wagatsuma Kazuaki
Institute for Materials Research, Tohoku University, Katahira, Sendai, Japan.
Anal Sci. 2011;27(4):453. doi: 10.2116/analsci.27.453.
The composition dependence of the emission intensities was investigated in Cu-Ni as well as Ni-Zn binary alloy samples when a low-pressure argon laser-induced plasma was employed as the excitation source. The calibration curve in the Cu-Ni alloy system gave a linear relationship, implying that the selective evaporation of Cu or Ni atoms was caused less in those alloys having several chemical compositions. The Cu-Ni binary alloy has a solid solution phase all over the chemical compositions (all-proportional solid solution): Cu and Ni atoms form no intermetallic compounds but can occupy any positions of a face-centered cubic lattice without any particular interaction. This metallurgical structure would enable Cu and Ni atoms to be released from the sample surface individually, which means that the amount of ablation corresponds to the chemical composition of the alloy sample. For a comparison, a Ni-Zn binary alloy system was also investigated to find calibration curves yielding a nonlinear relationship, differing from those of the Cu-Ni alloy. The reason for this is that the Ni-Zn binary alloy has several metallurgical phases comprising different intermetallic compounds which would each vary the evaporation behavior of Zn. It should be paid attention in LIPS that the ablated composition after laser irradiation is sometimes different from the chemical composition, depending on the kinds of samples and their metallurgical structures.
当使用低压氩激光诱导等离子体作为激发源时，研究了Cu-Ni以及Ni-Zn二元合金样品中发射强度与成分的关系。Cu-Ni合金体系中的校准曲线呈现线性关系，这意味着在具有多种化学成分的合金中，Cu或Ni原子的选择性蒸发较少。Cu-Ni二元合金在整个化学成分范围内都具有固溶体相（全比例固溶体）：Cu和Ni原子不形成金属间化合物，但可以占据面心立方晶格的任何位置，且不存在任何特殊相互作用。这种冶金结构使得Cu和Ni原子能够分别从样品表面释放出来，这意味着烧蚀量与合金样品的化学成分相对应。为了进行比较，还研究了Ni-Zn二元合金体系，发现其校准曲线呈现非线性关系，与Cu-Ni合金不同。其原因是Ni-Zn二元合金具有几个包含不同金属间化合物的冶金相，这些相各自会改变Zn的蒸发行为。在激光诱导击穿光谱法中应注意，根据样品种类及其冶金结构，激光辐照后的烧蚀成分有时会与化学成分不同。
