Effect Of TiC Particles On The Microstructure And Properties Of Al-Cu-Mg Alloy

In recent decades,aluminum alloys have been widely used in various fields,but they are limited in high-precision industries due to its low strength and poor abrasion resistance.Therefore,an enormous amount of research effort goes into the fabrication and performance improvement of particle reinforced aluminum matrix composites owing to the characteristics with high strength and abrasion resistance,as well as excellent high temperature performance.In this paper,nano-TiC particles were added to 2618 aluminum alloy,and then the large plastic deformation were carried out.The microstructure,abrasion resistance,high temperature creep resistance and corrosion resistance of the TiC/2618 composite were explored after plastic deformation and heat treatment.The main research contents and progress are as follows:(1)The original coarse dendritic structure of the as-cast 2618 aluminum alloy gradually transformed into fine equiaxed structure owing to the heterogeneous nucleation effect of nano-TiC particles after the nano-TiC particles were added.The fine grain was found with the addition of nano-TiC particles and the dynamic recrystallization produces fine grain after deformation.In addition,the volume fraction of recrystallization increases during the heat treatment process,and the volume fraction of recrystallization first increases and then decreases.The room temperature mechanical properties of 2618 aluminum alloy increases with the addition of nano-TiC particles.When the TiC content reaches 0.5 wt%,the TiC/2618 composite exhibited an ultimate tensile strength of 485 MPa with an elongation of 12.7%,which is 18.6%,7%higher than the 2618 matrix(409 MPa and 11.8%),respectively,owing to the precipitation of phases S(Al₂Cu Mg)and S'(Al₂Cu Mg)during the heat treatment process.Additionally,a large number of dislocations accumulated to form dislocation walls.Meanwhile,the interaction between high density dislocation and precipitated phase is conducive to improving the mechanical properties during plastic deformation.(2)The friction and wear tests were performed for heat-treated 2618 aluminum alloy with 0.5 wt%TiC.The wear rate and wear coefficient first decreased and then increased with the addition of nano-TiC particles.When the TiC content reaches 0.5wt%,the wear rate and wear coefficient both reached the lowest value.In fact,a small amount of nano-TiC particles are evenly distributed in the matrix,which can effectively support the worn surface.With the increase of the content of nano-TiC particles,the reinforcement agglomerated in the grain interior and grain boundary cannot achieve the original supporting effect,which leads to the decrease of wear rate.(3)The high temperature creep properties of heat-treated 2618 aluminum alloy with 0.5 wt%TiC were also tested.The creep resistance of TiC/2618 composite material first increases and then decreases with the increase of nano-TiC particles.The stable TiC particles at high temperature can effectively hinder the movement of grains and dislocations,and thus strengthen the material properties.(4)The corrosion experiments of intergranular corrosion,electrochemical corrosion and slow-strain rate stress corrosion all showed that the addition of nano-TiC particles is beneficial to improve the corrosion resistance of 2618 aluminum alloy.When the content of TiC reaches 0.5 wt%,2618 aluminum alloy has a higher corrosion resistance.In addition,the results of slow-strain rate stress corrosion indicated that the tensile strength of TiC/2618 composite in 3.5%Na Cl solution was lower than that in air.