Preparation And Mechanical Property Characterization Of Nanostructured Al-Si Alloy

One of the motivations for the development of materials science is to enhance thestrength of the material. To investigate and get combined strength and ductilitymaterial at a higher strength is one of the most active areas in the research of metalstructural materials. In which nanostructured materials are the most important part. Inrecent years, some research areas such as preparation, characterization, mechanicalproperty and deformation mechanism of the nanostructured materials have maderemarkable progress. The strength of the nanostructured materials is much higher thantraditional structural materials, but the ductility is very poor. Therefore, if the materialhas both high strength and good ductility, then it will have a prospective application inthe industry.In this work,1wt%silicon was added to high purity aluminum, after cold rolled toa reduction of98%, the material then was annealed at various temperature and holdingtime. The experimental techniques including Electron Channel Contrast （ECC）,Electron Backscatter Diffraction （EBSD）, Transmission Electron Microscopy （TEM）and microhardness testing were employed to study the features of microstructure,micro-texture and misorientation distribution. Tensile testing was carried out toinvestigate the influence of second phase silicon particles on the mechanical propertiesof Al^-1.0%Si alloy. The main results are as follows:①Nanostructured Al^-1.0%Si alloy with homogeneous microstructure is preparedby heavy cold rolling. The spacing between lamellar dislocation boundaries is230nm.②Three types of second phase particles are presented in as deformed Al^-1.0%Sialloy. The particles size is5.7μm,0.65μm and16nm separately.③A good combination of strength and ductility is obtained from nanostructuredAl^-1.0%Si alloy. The strength can reach210MPa, and the elongation is more than15%.The plastic instability phenomenon, which exists in the other nanostructured Almaterials, is effectively avoided and the appearance of negative deviations ofHall-Petch relationship is delayed.④The strain rate sensitivity parameter of nanostructured Al^-1.0%Si alloy is0.04.When the strain rate is more than1×10^-2s^-1, a passivation of strain rate sensitivity isobserved. And when the strain rate is more than1×10^-1s^-1, the strain rate sensitivity has a negative parameter.