Preparation And Properties Of Nickel-based Superalloys

This paper describes the status of research and development of ODS nickel-based superalloy,manufactured by Powder metallurgy technology,Preparation of pre-alloyed powders by high energy ball milling,through molding,high temperature vacuum sintering,the alloy is finally prepared in metallographic analysis?OM analysis?,X ray diffraction?XRD?,scanning electron microscopy?SEM?,energy spectrum analysis?EDS?,the powder particle size distribution test,sintering sample density test,fracture toughness calculation,hardness test and detection analysis method,studies the ball grinding process,pressing process,and the addition of rare earth oxides on the microstructure and the influence of the performance.Finally,explore the impact of Si elements on the antioxidant properties of the alloy at high temperature.After a series of research,draw the following conclusions:?1?Milling time for 32 h,ball material ratio of 20:1,When the ball milling speed is 400 rpm,alloy powder alloying showing a smaller particle size and higher hardness and the milling speed powder particles grow up tendency,compared with the same milling time and milling speed different ball to powder ratio of alloy powder were compared.It was found that the ball to powder ratio of 20:1 alloy refinement effect has to be better than 10:1.The speed of the ball material ratio of 20:1,alloy powder particle size was increased first and then decreased,and finally reaches a steady trend.Comprehensive show that the better ball milling process parameters: speed ball material ratio of 20:1,ball milling time for 32 h.?2?After ball milling powder will work hardening,in a certain range,with the increase of powder annealing temperature,the microhardness of the powder is decreased,the annealing temperature of 800?,the sintering density reached the ideal state.The powder is pressing process and in a certain range,with the increase of pressing force,the compact density increased rapidly and then leveled off.When the pressure is 175.16 MPa,the organization of alloy is uniform and compact.The tensile strength of the alloy increases with the increase of temperature decreased slowly at first,when the temperature exceeds the critical temperature?350⁴00 degrees?,the tensile strength of the alloy a sharp decline,and the fracture mechanism of the alloy by transgranular fracture gradually to intergranular fracture.?3?when adding 0.08% La₂O₃ dense material degree of 92.02%,the hardness of 544 HV and fracture toughness of 12.13 MPa·m1/2;when added to the alloy 0.08%La₂O₃,it can refine the organization in a certain extent,while reducing sintering of decarburization reaction,the toughening particles distribute more uniformly;adding an excess of La₂O₃,the polarization effect of rare earth elements will lead to its activity decline;to this kind of nickel based high-temperature alloy adding La₂O₃ can obviously improve the wear resistance of alloys in high speed and high load.And after the addition of La₂O₃ alloy in high speed and high load of friction coefficient and wear volume was significantly lower than that in low load and low speed under the.This is due to the friction surface formed a layer of enamel layer.The alloy of rare earth La₂O₃ optimum adding amount of 0.08%.?5?Adding an appropriate amount of Si element can increase the tensile strength and density of the nickel base alloy.After adding Si,the alloy density increased from 87% to 94.7%,the tensile strength increased from 340.96 MPa to 722.71 MPa,the fracture mechanism of the alloy is brittle and ductile diffusion coexist the original fracture to transgranular fracture can accelerate the.Si elements in the matrix,no remnants of second phase strip alloy added with Si element,after adding Si elements and the second phase into a ball,and high temperature oxidation resistance of the material has been greatly enhanced,increasing the ball material to improve oxidation resistance the alloy ratio can also,but the effect is less than the addition of Si.When the oxidation of 0.2%Si containing alloy 100 h at a temperature of 1000 DEG C after the oxide film is only about 45 m,and the film is more compact and complete,can Effectively protect the matrix from further oxidation.