Intergrowth microstructure and superior wear resistance of (TiB + TiC)/Ti64 hybrid coatings by gas tungsten arc cladding

• Published in: Materials & design Vol. 162; pp. 34 - 44
• Main Authors: An, Qi, Huang, Lujun, Jiao, Yang, Bao, Yang, Zhong, Bo, Geng, Lin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2019; Elsevier
• Subjects: Gas tungsten arc cladding; Hardness; Hybrid TiB + TiC reinforcements; Microstructure; Titanium matrix composite coatings; Wear; Titanium matrix composite coatings; Gas tungsten arc cladding; Hybrid TiB + TiC reinforcements; Microstructure; Hardness; Wear
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2018.11.039

For the sake of enhancing hardness and wear resistance of Ti based materials, 50 vol% (TiB + TiC)/Ti64 composite coatings with different TiB/TiC ratios were fabricated by gas tungsten arc cladding (GTAC) on the network structured 3.5 vol% TiBw (TiB whisker)/Ti64 substrate. The results showed that primary TiB and TiC exhibited much larger sizes than their eutectic counterparts, and the two-scale reinforcements formed by the dissolution-precipitation mechanism predominated the hybrid coatings. In particular, most TiC was embedded within the TiB prism displaying an intergrowth structure with “dissimilar-joining” characteristic, which contributed to the hardness and wear resistance improvement. The remarkable hardness improvement was attributed to the following three-fold mechanisms: (a) load transfer strengthening from the primary TiB and TiC; (b) Orowan strengthening from the eutectics; and (c) Hall-Petch strengthening from the refined Ti64 matrix. Moreover, the plastic deformation resistance was significantly improved by the hybrid reinforcements, leading to the enhanced the anti-abrasion performance. Consequently, the coating exhibited a comparatively low wear rate (7.35 × 10−5 mm3·N−1·m−1) compared with the substrate (54.89 × 10−5 mm3·N−1·m−1), and the corresponded wear mechanisms are summarized as: brittle debonding, oxidation and slight micro-ploughing. [Display omitted] •(TiB + TiC) hybridly reinforced Ti64 coating was fabricated by low-cost arc cladding.•Wear resistance is about 7 times higher than substrate with brittle debonding wear mechanism.•Revealing evolution characteristics of hybrid reinforcements and intergrowth structures.•Property enhancing mechanism is revealed by mechanical tests under various load magnitudes.