Papers by Author: Yuan Ding Huang

Abstract: It is importance to be able to predict the hot tearing tendency for multicomponent magnesium alloys. Hot tearing is one of the most common and serious defects that occurs during the solidification of commercial magnesium alloys. Clyne and Davies correlated the susceptibility-composition relationship in binary systems based on the concept of the existence of critical time periods during the solidification process when the structure is most vulnerable to cracking. The present work first evaluates the hot tearing susceptibility (HTS) of binary Mg-Zn system using thermodynamic simulations based on Clyne-Davies’ model, a typical “λ shape” curve is obtained. And then a scaling factor is investigated to obtain the internal-consistent cracking susceptibility coefficient for further investigating the addition of aluminum on the HTS in the ternary Mg-Zn-Al system. The predicted hot tearing tendencies is consistent very well with the experimental results of the Mg-Zn binary system and Mg-Zn-Al ternary system.

Abstract: A homogeneous microstructure of as-cast magnesium alloys is necessary to improve the formability during their subsequent thermomechanical processing. In Al-containing magnesium alloys, the grain refinement by carbon inoculation is considered to be the best approach until now. However, the mechanism of grain refinement is unclear. The present work investigates the coring microstructure in Mg-Al alloys inoculated with carbon using FIB, SEM and TEM techniques. In each grain one or more “hillocks” exist, enriched with carbon, manganese and aluminium. This is possibly related to the inhomogeneous nucleation of alpha-magnesium. The precipitates in these “hillocks” are always surrounded by the aluminium-rich zones. These characteristics of microstructure observed in Mg-Al alloys with carbon inoculation are compared with that observed in Al-free magnesium alloys inoculated by zirconium. The similarities between them are discussed. A novel mechanism is suggested to explain the grain refinement in Mg-Al alloys inoculated by carbon.

Abstract: The present paper presents the development status of creep resistant magnesium materials. It reviews the creep deformation mechanisms of magnesium alloys. Based on these mechanisms, several effective approaches to improve the creep resistance are discussed, including alloying, microstructural control and the development of new monolithic alloys and composites.