Microstructure And Properties Of Pt-Ir-Hf And Pt-Ir-Y Superalloys

Platinum-based alloys are used as high temperature structural materials with ex-cellent high temperature endurance strength,creep fracture strength,oxidation re-sistance and corrosion resistance,as well as good creep resistance at high temperature.They play an irreplaceable role in the field of aerospace.A new generation of aerospace engine application in our country has great demand to the ultra high temperature struc-tural materials,using?/?'precipitation strengthening the development of nickel base alloy,it needs to design and develop platinum based high temperature alloy,solid solu-tion strengthening of existing mature type platinum alloy such as Pt-Ir alloys can't meet the requirements for the comprehensive performance of Ir alloy materials,that need to have solid solution strengthening and?'development phase precipitation strengthening the combination of new type composite strengthening platinum alloys.In view of the significant demand of aerospace applications for ultra-high temperature structural mate-rials,this study carried out the relationship between the microstructure and properties of new Pt-Ir-Hf and Pt-Ir-Y alloys,which is of great significance for the selection of plati-num-based superalloy materials.In this paper,on the basis of solid solution reinforced Pt-15Ir alloys,the third component Hf and Y were added to explore the relationship between the microstructure and properties of the two alloys Pt-Ir-Hf and Pt-Ir-Y.The Hf and Y elements distributed matrix in the alloy,the second phase and the interface was analyzed and the alloys me-chanics was tested.The strengthening mechanism of the two alloys was analyzed in depth.The results are as follows:(1)Addition of Hf element,which is solidly soluble in Pt-Ir solid solution matrix;when 1%of Hf is added,it is completely solidly soluble in the alloy matrix;when 3%of Hf is added,part of Hf is solid dissolved in the alloy matrix,and part of Hf forms a dispersed L1₂ structure(Pt,Ir)₃Hf nanometer second phase in the alloys matrix.(2)The composite strengthening mechanism of Pt-Ir-Hf alloys includes:solid solu-tion strengthening,second phase strengthening,fine grain strengthening.The addition of Hf has a good strengthening effect.With the increase of Hf content,the precipitation of nano-scale?'-(Pt,Ir)₃Hf second phase strengthens effectively in the matrix,while the solid solution effect is enhanced,and there are obvious grain refinements.That the me-chanical properties of the alloys have been greatly improved.The performance test shows that the hardness of the alloy with Hf has been greatly improved.After adding 3%Hf,the hardness of the alloy has the largest increase,and the increase rate is about 75%.(3)With the addition of Y element,only a small amount of Y was dissolved in the Pt-Ir solid solution matrix.When 0.5%and 1%of Y were added,Y was mainly distrib-uted in the grain boundary preferentially,and a second phase of(Pt,Ir)₃Y structure type was formed in the grain boundary.When 1%of Y is added,the second phase precipitates out on the grain boundary in a continuous distribution,and a small amount of dispersed second phase precipitates out on the solid solution matrix.(4)Pt-Ir-Y alloy strengthening has obvious grain refinement and second phase strengthening.This shows that the addition of Y improves the mechanical properties of the alloy.The performance test shows that the hardness of the alloy increases with the addition of Y.After adding 1%Y,the hardness of the alloy increases the most with an increase rate of 54.2%.(5)After Pt-Ir-Hf and Pt-Ir-Y alloys are stabilized at different temperatures,Hf and Y are oxidized precipitate oxides at the grain boundaries of the alloy,and the oxides in-crease as the temperature increases;Pt-Ir-Hf and Pt-Ir-Y alloys have a certain decrease in hardness after treatment,but the hardness remains basically unchanged after treat-ment at different temperatures.In summary,this paper studied the constitution-structure-performance relationship of Pt-Ir-Hf and Pt-Ir-Y alloys,paper analyzed the influence rule of Hf and Y elements on the metallographic structure,It revealed the internal strengthening mechanism.It is found that the addition of Hf has a good strengthening effect,and the results are greatly significance for the design of platinum-based superalloys.