Effect Of Heat Treatment On Microstructure And Mechanical Properties Of M11Nickel-Based Superalloys

Nickel-based superalloy plays an important role in the field of superalloys. And as its merits, such as high working temperature is, good structure stability and high resistance of oxidation and corrosion, the nickel-based superalloy is being widely used in the Manufacture of aviation jet engines, the hottest parts of variety of industrial gas turbine and so on. The main strengthen phase of nickel-base superalloys are Ni3(Al, Ti, Nb) intermetallic compound (y’phase) and carbides, the strengthen phase with appropriate morphology, quantity, size and distribution can make alloys with good over-all properties.In the present study, M11nicked-based superalloy was chosen as object of material, the effect of heat treatment on γ’ phase, grain boundary carbide phase, eutectic phase, grain boundary element distribution and stress-rupture property have been systematically investigated by using metallographic microscope(OM), scanning electron microscope(SEM), electron probe microanalyzer(EPM). The primary coverage is as follows:(1)The γ’ phase after heat treatment was analysised through scanning electron microscope shows that:with the solution heat treatment temperature rising, the size of γ’ phase deceases, the quantity increase, the distribution is uniform and the morphology into a cube shape; with the intermediate heat treatment rising, the size and quantity of γ’ phase deceases, the morphology and distribution has little change; with the aging heat treatment temperature rising, the size and quantity of γ’ phase increases, the morphology and distribution has little change.(2)The carbide of grain boundary after heat treatment was analysised through scanning electron microscope shows that:with the aging heat treatment temperature rising, the size of Cr23C6carbide of grain boundary increases, the quantity increases and then decreases, the morphology is discontinuous chain; the size and quantity of Cr23C6carbide of grain boundary of the alloy after solution heat treatment compare to the alloy without solution heat treatment is larger and its morphology is continuous chain.(3)The (γ+γ’) eutectic after heat treatment was analysised through metallographic microscope shows that:(γ+γ’) eutectic is difficult to dissolve when the solution temperature below1210℃and (γ+γ’) eutectic is quick to dissolve when the solution temperature above1210℃.(4) The C element segregation after heat treatment was analysised through electron probe microanalyzer shows that:C element segregation in the grain boundary can be reduced by heat treatment.(5)The stress-rupture experiment under870℃/370MPa shows that:stress-rupture life of alloy after solution heat treatment compare to the cast alloy has little change.(6)Determine the heat treatment system of alloy is that:without solution heat treatment, intermediate heat treatment temperature is1120℃and aging heat treatment temperature is850℃.