Chengwu Yao

In situ synthesised WC reinforced nickel coating by laser cladding

ABSTRACT Using tungsten, carbon, and nickel powder as raw materials, an in situ synthesised WC reinforced nickel matrix (marked as IWC) coating was fabricated on a mild steel by laser cladding. The experimental results showed that a large number of WC particles were in situ synthesised and homogeneously distributed in the coating with free of pores and cracks. Compared with the steel substrate, an improvement of micro-hardness value (2.6 times) was observed for the IWC coating. Sliding wear test showed that the IWC coating has stable friction coefficient, and possesses higher anti-wear property under 300 N than ex situ WC reinforced coating.

Relationship between the γ and some parameters of Fe-based bulk metallic glasses

Abstract The relationship between γ (Tx/(Tg + Tl)) of Fe-based bulk metallic glasses (BMGs) and three parameters (i. e., electronegativity difference, atomic size parameter and heat of mixing) is studied in this paper. The conclusion can be drawn from the available experimental data in the literature that parameter γ has a close correlation to three parameters in Fe-based BMGs. It can be expressed as follows: γ = 0.40334 − 0.20242 × Δx2 − 0.1209 × δ2 + 3.7395 × 10−6 × ΔH2. The function can be obtained by a nonlinear regression analysis program and it can be used to find new Fe-based BMGs alloys.

Effect of Isothermal Temperature on Growth Behavior of Nanostructured Bainite in Laser Cladded Coatings

The growth and propagation behavior of austenite-to-bainite isothermal transformation in laser-cladded, Si-rich, and Fe-based coatings is investigated. The crystallographic features, orientation relationship at different isothermal temperatures, and the morphology of the nanostructured bainite are determined. The Nishiyama-Wassermann type orientation relationship is observed at a high temperature and at a low temperature, and mixed Nishiyama-Wassermann and Kurdjumov-Sach mechanisms are seen. The growth direction is investigated by the partial dislocation theory and an extrapolated model based on the repeated formation of lenticular-shaped subunits and pile-up along the close-packed directions of the close-packed planes. The variants of the bainite growth directions would be more selective at the high transformation temperature.

High Power Diode Laser Cladding of Hard Fe-based Coatings

Three types of Fe-based coating for high hardness, including low-temperature bainitic coating, particle reinforced martensite coating and amorphous coatings, have been prepared on mild steel by using high power diode laser cladding.