Preparation And High Temperature Mechanical Properties Of Co-continuous Phase Ti₃AlC₂/2024Al Matrix Composites

The ternary layered ceramic material Ti₃AlC₂has the excellent properties of both ceramic and metal,and 2024Al has excellent electrical conductivity,thermal conductivity and corrosion resistance.With 2024Al as metal matrix and Ti₃AlC₂as reinforcement phase,composite materials with excellent comprehensive properties are expected to meet the requirements of light weight,high strength,wear resistance and good interface bonding in the field of mechanical engineering.In this paper,Ti powder,Al powder,Sn powder and Ti C powder were used as the initial raw materials to prepare porous Ti₃AlC₂with different porosity by in-situ reaction sintering method.Then,the molten metal 2024Al was impregnated into the preform under vacuum and no pressure condition to obtain Ti₃AlC₂-2024Al matrix double-continuous phase composites.On this basis,the influence of the porosity of the preform,the grain size and morphology of the ceramic phase on the microstructure,phase structure and mechanical properties of the Ti₃AlC₂-2024Al bi-continuous phase composite was systematically analyzed.The high temperature mechanical properties and thermal shock resistance of Ti₃AlC₂/2024Al double continuous phase composites were tested and analyzed.The preform Ti₃AlC₂ was prepared by sintering with pressure-free sintering method.The required raw material powder was Ti powder:Al powder:Sn powder:Ti C powder,and the molar ratio was 1:1.1:0.1:1.78.The porous Ti₃AlC₂preforms with adjustable porosity were prepared by sintering at 1450?for 10 min,20 min and 30min under cold axial pressure of 50 MPa.The apparent porosity of porous Ti₃AlC₂preforms is 48%,41%and 35%,respectively.The interior is loose and porous with good shape retention,which completely meets the requirements of the preform without pressure infiltration.The Ti₃AlC₂/2024Al matrix composites with good density and three-dimensional network continuous distribution of ceramic and metal phases were obtained by adopting the infiltration process at 930?and holding for 3 h.In the leaching process,2024Al reacts with part of Ti₃AlC₂to form Al₃Ti and Ti C.In the process of holding for 3h,Ti₃AlC₂was eroded into fine particles by 2024Al from the large lumps before,and some Ti C particles and bar Al₃Ti were distributed around Ti₃AlC₂.Because of its special growth mechanism,the rod-like Al₃Ti can effectively connect the Ti₃AlC₂skeleton to further enhance the continuity of ceramic skeleton..The mechanical properties of Ti₃AlC₂/2024Al matrix composites prepared are excellent.With the decrease of porosity of the preform,the mechanical properties of the composite at room temperature are improved.The bending strength of65Ti₃AlC₂/2024Al can reach 593MPa,and the hardness is 2.74GPa.The compressive strength is 734MPa and the fracture toughness Kic is 6.61MPa.M^1/2.The prepared Ti₃AlC₂/2024Al matrix composites with different ceramic contents have excellent high temperature mechanical properties and thermal shock resistance.Under the conditions of300?and 400?,the bending strength of 52Ti₃AlC₂/2024Al is 442MPa and the compression strength is 532 MPa.The thermal shock resistance of Ti₃AlC₂/2024Al matrix composites with different ceramic contents was tested at 400?and in the air atmosphere,of which was found The residual bending strength of 52Ti₃AlC₂/2024Al is450MPa.It's only 5%less intense than it was before the hot shock.The excellent thermal shock resistance of the composites is attributed to the excellent interface bonding of the double-continuous phase composites and the resulting rod-like Al₃Ti,which further improves the continuity of the ceramic framework of the composites and makes the composites have excellent thermal shock resistance.