Nanoindentation Characterization on Microhardness of Micron-Level TiC and TiB Reinforcements in in-situ Synthesized (TiC+TiB)/Ti-6Al-4V Composite

Yan Wen,Tingting Guo,Huiping Bai,Yuangui Zhou,Zhou Wang

doi:10.3389/fmats.2019.00205

Abstract

The microhardness of micro-level TiC and TiB reinforcements in in-situ synthesized (TiC+TiB)/Ti-6Al-4V composite were investigated independently by spherical nanoindentation. The morphology of indentation on the matrix, reinforcements and the reinforcement / matrix interfaces were characterized by scanning electron microscope (SEM). The influence of cracks on the load-displacement curves and microhardness were analysed and discussed. The microhardness of TiC and TiB were calculated from the load-displacement curves on reinforcements without cracks. The average microhardness of TiC and TiB in this composite were 24.1 and 19.6 GPa, respectively, which agreed with the values in other composites and coatings. These results verified that the nanoindentation method was a very useful method to characterize the microhardness of micron-level reinforcements in discontinuous metal matrix composite.

Highlights

The generated TiB are nearly parallel to the axial direction because of the realignment during hot forging
There is no obvious effect on TiC particles since the shapes of TiC are globular, near globular or ellipsoid
The depth of indentation on TiB with cracks is maximum at 160 nm, which is different from that on TiC (Figure 2e), this phenomena may be caused by the large number of cracks on TiB during loading (Figure 3c), and the propogation of cracks results in the fast penetration of indenter on the surface of TiB

Summary

Introduction

Due to the high specific strength, good specific modulus, and high strength at elevated temperature, titanium matrix composites (TMCs) have wide application prospects in the fields of aerospace, automobile and other industries (Tjong and Ma, 2000; Zhang et al, 2006, 2018; Huang et al, 2015; Zhang and Attar, 2016; Huang and Geng, 2017; Xie et al, 2018a; Wang et al, 2019; Zhang and Chen, 2019). The SEM images of indented imprint on matrix and TiC reinforcements are shown in Figure 2 for the case of peak loading at 60 mN.

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Conclusion