Study On Forging Microstructure And Properties Of SiCp/2009 AL Composites

SiCp/Al composites have been gradually used in aviation industry because of their excellent properties.But because of the limitation of size,the super-large parts must adopt forging technology to realize hot processing.Therefore,the research and analysis of particle reinforced aluminum matrix composites forging process can provide theoretical support and technical guidance for the actual SiCp/Al composites forging.In this paper,the powder metallurgy15vol%SiCp/2009Al composite was used as the original sample.The thermal compression experiment was carried out on a thermal simulation machine.The thermal deformation constitutive equation and thermal working diagram of the composite were analyzed and constructed.Forging experiments of?100×100mm block material were carried out by using the optimal deformation parameters.Several groups of unforged and forged samples were analyzed by means of metallography,scanning,transmission,3D-XRD,EBSD and tensile methods.The influence rule of microstructure of forged materials on mechanical properties of samples under different processes was obtained.The constitutive equation of 15vol%SiCp/2009Al composite with Z parameter in hyperbolic sinusoidal form is constructed.The processing diagram suitable for 15vol%SiCp/2009Al matrix composites was established.The laws for the?values(power dissipation efficiency factor)and?values(instability criterion)in SiCp/2009Al composites are similar.The maximum strain rate is 1s^-1 at 520^oC and the minimum strain rate is 0.001s^-1 at 520^oC.The hot working temperature and strain rate of 15vol%SiCp/2009Al composites are determined to be 480^oC and1mm/s.The mechanical properties of the forged samples were obtained.Generally speaking,the mechanical properties of the forged samples have been improved widely.When the deformation amount is the same in the same pass and the deformation amount is different in the same pass,the change rule of mechanical properties is firstly increased and then decreased.When the total deformation is the same,the mechanical properties are better with fewer heating times.The influence of microstructure characteristics on mechanical properties of the composites under different forging processes was clarified.With the change of deformation amount and forging times,the effect of microstructure on mechanical properties is mainly the second phase precipitated by strain,and the change of grain distribution and grain size is the second phase.First of all,the increase of deformation will make the SiC particle distribution of composites more dispersed,which will improve the properties of the materials.Secondly,with the increase of heating times,the grain size of the composite material gradually grows up,which will reduce the properties of the material.Finally,the second phase precipitation is induced by obvious geo-strain,so the precipitation rule of Al₂Cu second phase is as follows:with the increase of deformation,?phase first disperses in small amount,then precipitates in small amount,and finally precipitates in regular acicular arrangement.This is roughly the same as the change law of mechanical properties of materials.