Effects of high temperature treatment on microstructure and mechanical properties of laser-clad NiCrBSi/WC coatings on titanium alloy substrate

Journal Article · Mon Dec 15 00:00:00 EST 2014 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2014.10.003· OSTI ID:22403604

Li, Guang Jie; Li, Jun; Luo, Xing

Laser-clad composite coatings on the Ti6Al4V substrate were heat-treated at 700, 800, and 900 °C for 1 h. The effects of post-heat treatment on the microstructure, microhardness, and fracture toughness of the coatings were investigated by scanning electron microscopy, X-ray diffractometry, energy dispersive spectroscopy, and optical microscopy. The wear resistance of the coatings was evaluated under dry reciprocating sliding friction at room temperature. The coatings mainly comprised some coarse gray blocky (W,Ti)C particles accompanied by the fine white WC particles, a large number of black TiC cellular/dendrites, and the matrix composed of NiTi and Ni{sub 3}Ti; some unknown rich Ni- and Ti-rich particles with sizes ranging from 10 nm to 50 nm were precipitated and uniformly distributed in the Ni{sub 3}Ti phase to form a thin granular layer after heat treatment at 700 °C. The granular layer spread from the edge toward the center of the Ni{sub 3}Ti phase with increasing temperature. A large number of fine equiaxed Cr{sub 23}C{sub 6} particles with 0.2–0.5 μm sizes were observed around the edges of the NiTi supersaturated solid solution when the temperature was further increased to 900 °C. The microhardness and fracture toughness of the coatings were improved with increased temperature due to the dispersion-strengthening effect of the precipitates. Dominant wear mechanisms for all the coatings included abrasive and delamination wear. The post-heat treatment not only reduced wear volume and friction coefficient, but also decreased cracking susceptibility during sliding friction. Comparatively speaking, the heat-treated coating at 900 °C presented the most excellent wear resistance. - Highlights: • TiC + WC reinforced intermetallic compound matrix composite coatings were produced. • The formation mechanism of the reinforcements was analyzed. • Two precipitates were generated at elevated temperature. • Cracking susceptibility and microhardness of the coatings were improved. • Post-heat treatment enhances wear resistance of the coatings.

• OSTI ID: 22403604
• Journal Information: Materials Characterization, Vol. 98; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM CARBIDES
COATINGS
CRACKING
FRACTURE PROPERTIES
FRICTION FACTOR
HEAT TREATMENTS
INTERMETALLIC COMPOUNDS
MATRIX MATERIALS
MICROHARDNESS
MICROSTRUCTURE
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
SLIDING FRICTION
SOLID SOLUTIONS
SUBSTRATES
TEMPERATURE DEPENDENCE
TITANIUM ALLOYS
TUNGSTEN CARBIDES
WEAR RESISTANCE
X-RAY DIFFRACTION