AFM的纳米硬度测试与分析

基于原子力显微镜(AFM)和金刚石针尖建立了一套纳米压痕测量系统。通过向系统发送控制电压使金刚石针尖在完成加载和卸载全过程的同时进行实时的数据采集并直接绘出载荷-压深曲线。利用该系统,对单晶铝和单晶铜薄膜材料进行了单点压痕实验,用美国Hysitron公司的纳米原位测量仪(TriboIndenter)做了验证试验。实验结果表明,该系统适合测量较软材料的纳米硬度。分析了基体材料对薄膜硬度和弹性模量的影响,在薄膜厚度低于5~10倍压入深度时,基体对薄膜材料的力学性能影响很大;并根据获得的载荷－压深曲线分析得出由于尺度效应的影响,随着压痕深度的减小,薄膜的硬度值呈明显的上升趋势,弹性模量没有这个趋势。

Test and analysis on nanohardness using an AFM-based system

A system based on atomic force microscope(AFM) and a (Berkovich) diamond tip was developed for nanohardness and elastic modulus measurements.This system can directly gain the load-displacement curves that couldn't be obtained from indent software of AFM itself.The diamond tip was controlled by sending signal to achieve loading and unloading and gathering the real-time data.In this way the load-displacement curve and data could be acquired directly. Single point experiments were conducted on single-crystal copper and single-crystal aluminum thin films.TriboIndenter produced by Hysitron Inc was used to do the validated experiments.The results show that the system is suited for nanohardness measurement of the softer materials.By analysis on the effects of substrate material on nanohardness and elastic modulus,it can be known that the substrate has great influence on the mechanical characteristic of the film when the thickness of film is less than 5 to 10 times the peak depth.Nanohardness increases with a decrease in the indentation depth,which indicates a strong size effect,but there is no significant effect on the elastic modulus based the load-displacement curves.