Intergrowth microstructure and superior wear resistance of (TiB + TiC)/Ti64 hybrid coatings by gas tungsten arc cladding. (15th January 2019)

• Record Type: Journal Article
• Authors: An, Qi; Huang, Lujun; Jiao, Yang; Bao, Yang; Zhong, Bo; Geng, Lin
• Is Part Of: Materials & design. Volume 162(2019)
• Page Start: 34
• Page End: 44
• Publication Date: 2019-01-15
• Subjects: Titanium matrix composite coatings -- Hybrid TiB + TiC reinforcements -- Gas tungsten arc cladding -- Microstructure -- Hardness -- Wear; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2018.11.039
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: 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 mm 3 ·N −1 ·m −1 ) compared with the substrate (54.89 × 10 −5 mm 3 ·N −1 ·m −1 ), and the corresponded wear mechanisms are summarized as: brittle debonding, oxidation and slight micro-ploughing. Graphical abstract: Highlights: (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.