Papers by Author: Qing Wei Jiang

Abstract: The Ti-48at%Al composite powder was synthesized by high energy ball milling. The properties of the composite particles, such as medium diameter,Phase ,microstructure and components, were respectively investigated . Results show that, the phase evolution process can be described by: Ti+ Al fcc Ti (Al),TiAl,TiAl₃,Ti₃AlTiAl₃,Ti₃Alamorphous phase. After milling 3 hours, Fcc Ti (Al) solid solution, TiAl, TiAl₃, Ti₃Al were found. After milling 9 hours, the amorphous phase of Ti - 48 at % Al were produced. The element distribution of the mechanically alloyed Ti-48at%Al powder was close to the initial design composition after 5 h milling, but this distribution was inhomogeneous. Medium diameter (D₅₀) of Ti-48at%Al composite powder achieved the minimal size 9.56 μm after milling for 5hours.

Abstract: The temperature-dependent deformation and damage behaviors of ultrafine-grained (UFG) Cu and Ti produced by equal channel angular pressing (ECAP) were investigated and compared. It was found that ECAPed materials with different crystalline structures, e.g. the present fcc Cu and hcp Ti, exhibited significantly distinctive high-temperature deformation and damage characteristics. As the testing temperature is below recrystallization, small- and large-scale cracks or voids formed along the shear bands (SBs) on the surface of UFG Cu, whereas only a few fine shear lines and some non-propagation voids appeared on the surface of UFG Ti. As the temperature is above recrystallization, some small cracks (or voids) formed along grain boundaries and slip deformation took place in many coarsened grains, while only extrusions and intrusions instead of obvious cracks or voids are observable for UFG Ti. The corresponding microstructual changes after compressive deformation, e.g. grain coarsening, were also examined and confirmed by TEM observations.

Abstract: The individual or joint effects of annealing and equal channel angular pressing (ECAP) treatments on the high-temperature compressive deformation and damage behavior of cast LY12 Al alloys were studied. The compressive deformation behavior and surface deformation and damage characteristics of differently treated LY12 Al alloy samples were examined at temperatures ranging from 25°C to 400°C. It is found that the LY12 Al alloy exhibits different compressive mechanical behavior depending on different treatments, and the compressive deformation and damage characteristics of LY12 Al alloys with different microstructural states are closely related with the testing temperature. As compared to other samples (e.g. as-cast, annealed, as-cast+2ECAPed), the sample annealed at 450°C for 3h followed by ECAPed for 2 passages (i.e. annealed+2ECAPed) shows a better high-temperature deformation stability.