中文摘要：

研究不同水灰比条件下的钢纤维增强水泥基复合材料界面过渡区（ITZ）的纳米力学性能。通过纳米压痕试验，测试界面过渡区及其附近区域的荷载-压痕深度曲线，运用Oliver-Pharr方法研究了弹性模量和硬度分布规律并绘制相应的微结构表征云图，结合扫描电子显微镜分析ITZ形成机制。此外，利用反褶积法对ITZ的弹性模量及压痕硬度的频率分布曲线进行多峰拟合，得到了各相的频率分布。结果表明：不同水灰比样品界面过渡区的厚度均为40μm左右；在界面过渡区内，弹性模量和压痕硬度的最弱点在距纤维表面20μm附近，且水灰比越大，弹性模量与压痕硬度值越小；随着水灰比的增大，界面过渡区孔洞和低密度水化硅酸钙含量逐渐增高，高密度水化硅酸钙含量逐渐降低。

英文摘要：

The nanoscale mechanical properties of interfacial transition zone （ITZ） in steel fiber reinforced cementitious composite for different water-cement ratios were investigated. The load-crack depth （P-h） curves of ITZ were determined via nanoindentation test. The distribution of elastic modulus and hardness were calculated and mapped in a 2D plane by the Oliver-Pharr method. The formation mechanism of ITZ was analyzed. In addition, the frequency distribution of different phases in ITZ was determined by a multi-peak fitting deconvolution method. The results indicate that there is a interface width about 40 pxn in all the cases. The minimum modulus and hardness occur at a distance of 20 ~tm from the steel fiber surface. The greater the water-cement ratio, the lower elastic modulus and hardness will be. The content of porosity and low density C-S-H gradually increase, and the density of C-S-H decreases with the increase of water-cement ratio.