TiN/Al_2O_3纳米多层膜的共格外延生长及超硬效应

Epitaxial growth and superhardness effect in TiN/Al_2O_3 nanomultilayers

采用多靶磁控溅射法制备了一系列具有不同Al2O3调制层厚度的TiN/Al2O3纳米多层膜.利用X射线能量色散谱、X射线衍射、扫描电子显微镜、高分辨透射电子显微镜和微力学探针表征了多层膜的成分、微结构和力学性能.研究结果表明,在TiN/Al2O3纳米多层膜中,单层膜时以非晶态存在的Al2O3层在厚度小于1·5nm时因TiN晶体层的模板效应而晶化,并与TiN层形成共格外延生长,相应地,多层膜产生硬度明显升高的超硬效应,最高硬度可达37·9GPa.进一步增加多层膜中Al2O3调制层的层厚度,Al2O3层逐渐形成非晶结构并破坏了多层膜的共格外延生长,使得多层膜的硬度逐步降低.

TiN/Al2O3 nanomuhilayers with various Al2O3 layer thicknesses were prepared by multi-target magnetron sputtering. The chemical composition, microstructure and mechanical properties of these muhilayers were characterized by energy dispersive X- ray spectrometry, X-ray diffraction, high-resolution transmission electron microscopy and nanoindentation. The result raveals that under the sputtering conditions, normally amorphous A12 03 is forced to crystallize at very small layer thicknesses （ 〈 1.5 nm）, and grows coherently and epitaxially over TiN layers. Correspondingly, the hardness of the muhilayers increases significantly and reaches a maximum value of 37.9 GPa. Further increasing in layer thickness, Al2O3 layers form an amorphous structure and block the coherent growth of the muhilayers, and thus the hardness decreases gradually.