Papers by Author: Jiang Wu

Abstract: High current pulsed electron beam (HCPEB) is a fairly new technique for improving surface properties such as corrosion and wear resistances. One of the negative effects induced by HCPEB is the potential formation of craters on the surface of the HCPEB treated materials. These changes can impair the corrosion-resistance by promoting pitting. The mechanisms of nucleation and growth are detailed and the effect of the number of pulses on crater formation is discussed.

Abstract: High current pulsed electron beam (HCPEB) is a fairly new technique for surface modifications, including hardening, alloying and formation of metastable phases. The present contribution gives some new insights on the microstructure modifications encountered at the top surface of HCPEB treated metals. In particular, the potential of the technique for structure modifications associated with the use of the pulsed electron beam under “heating” and “melting” conditions are highlighted.

Abstract: The present paper investigates the bulk metallic glass formation in Co-based alloy systems with the guidance of the cluster line and minor-alloying principles. The selected basic ternary Co-B-Si alloy compositions are intersecting points of cluster lines, defined by linking special binary clusters to the third element. Then these basic ternary alloys are further minor-alloyed with Nb and quaternary bulk metallic glasses are obtained only by 4-5 at. % Nb minor-alloying of the basic composition Co68.6B25.7Si5.7 that is developed from dense-packed cluster Co8B3. The bulk metallic glasses are expressed approximately with a unified simple composition formula: (Co8B3)1(Si,Nb)1. In addition, a quantity of Fe substitution for Co further improves the glass-forming abilities.

Abstract: Ternary Sm-Al-Co bulk metallic glass formation is investigated with the guidance of a cluster line approach which is defined by linking a special cluster composition to the third element in the ternary phase diagram. Two dense-packed cluster lines Sm6Al3Co2-Co and Sm8Al1Co4-Al are constructed and they intersect at a good BMG composition Sm50Al25Co25. This composition can also be interpreted with a cluster-plus-glue atom model. The characteristic parameters of this optimum BMG are respectively Tg = 579 K, Tx = 640 K, Trg= 0.648, γ = 0.435 and
E=244 kJ/mol.