Abstract:
The structures of standard heat treatment of the alloy have the phases of gamma, gamma prime, MC,M₆C and M₃B₂.
The first temperature rang of grain growth is about 1150-1170℃. The second is 1210℃. The maximum precipitation peak of main carbide phase M₆C is about 1000℃, and two kinds of M₆C differentiated between in compositions has been found in the tested alloys.
The standard heat trearment of the alloy do not get two kinds of gamma prime phase in size, but the isothermal treatment can get two kinds of gamma prime phase and zigzag grain boundary. The phase of M₂₃C₆ after ageing for a long time can be precipitated in the alloy which has low content of Mo, W, Al and Ti, If the content of W,Mo is greater than 12% （e.g 12.31%）, a few Mu phases can be precipitated.
The carbide can be changed in shape and fined in size,when the magnesinm is added to alloy.

Abstract:

Abstract:
The chemical composition and content of superalloy GH220, precipitation tendency ofγ’ and crystal structure, -misfit of gamma prime are studied. The effect of alloying elements on the content of gamma prime,on the growth rule and the change of its shape and size are researched.

Abstract:
The crystal structures, chemical composition, shapes, distribution and contents of M₆C, M₂₃C₆ and MC are studied. And their rules of dissolution, pricipitation and phase transformation each other are researched too.

Abstract:
The law of the phase precipitation and phase dissolution in alloy with different content of W, Mo, Al and Ti has been studied by the method of complex phase analysis. The main alloying elements influencing on the precipitated phase have been found, and phase transformation rule is got. The content of kinds of phases have been measured.

Abstract:
Chemical composition of gamma prime phase of alloy, the density of gamma, gamma prime and of alloy have been calculated with some formulae in references. The results of calculation agree with the measured results. span style="text-decoration:overline">NV and N_V^C in GH220 alloy with different content of W, Mo, Al, Ti and V are calculated too. There is not needlelike Mu phase if span style="text-decoration:overline">NV≤2.30.

Abstract:
Two kinds of heat-treatment method are used for Ni-base superalloys GHl51,GH37,GH33,and Fe-base supsralloys GH36 and GH69.The results show that the Zig-Zag grain boundaries are formed in air these alloys. It has been found that the mechanism of Zig-Zag G. 33. formation is dependent not only on heat-treatment method but on compositions of alloys.

Abstract:
The formation mechanism of Zig-Zag grain boundary and the action of adding some W, Mo, C, Ce（minor） to alloy have been probed tentatively.The results show that gamma prime well induce the formation of Zig-Zag G. B. when alloy is cooled slowly, and the carbides are the same too when the alloy coolled quickly or the isothermal heat treatment method is used. The best content ranges of W, Mo, C, Ce are found out, which is useful for production.

Abstract:
Fatigue property of alloy GH220 treated by two kinds of heat treatment have been tested.The results show that the fatigue limit of alloy treated by isothermal teat treatment is higher than that treatde by standard heat treatment. The reason of this difference is discussed in detail.

Abstract:
The behaviour of cyclic endurance failure have been researched under different conditions of temperature and hold time. Two kinds of heat treatment method are used to get the different structure of grain boundary. The results show that the alloy with both kinds of G.B. state are all not agreement with Linear - Damage Summation, t/tr +Nj/Nf = 1 under conditions of temperatuers 750, 800, 850, and 900℃, and hold time 0-32（min）. In general, all specimens are strengthened very clearly. There is great influence of hold time on the cyclic failure life of alloy. The peak of this life vs hold time is occurred. Trend of weakening is begun when hold time is shorter than 3 min.The micro - mechanism have been analyzed by means of TEM, SEM and "so" on. These phenomenon are explained with dislocation structures and anela-sticity.

Abstract:
Influence of ageing temperatures and times on aluminide coating structure is investigated in this paper. The results show that aged aluminide coating consist mainly of the outer and the inner layers. The outer layer includes Al2O3 oxide zone, β-NiAl zone and denuded zone. The inner layer includes rich C zone and needlelike phase zone. It has been concentrated on discussion of exhaustion mechanizm and: of reasons, of needlelike phase formation in aluminide coating.

Abstract:
Layer by layer phase analysis of aluminide coating of a Ni - base supe-ralloy GH220 is carried out by physicochemical phase aaalysis and other physical instruments. The used samples of this alloy is aged at different time. Contents of β- NiAl and γ’ phases within various depth from coating surface was determined through simultaneous equations. The reasonable calculation of removed coating thickness is mado by correcting density. Trend of phase transformation in alurninids coating is presented. All calculations in this paper are programmed. Application of microcomputer in phase analysis is initially tried.

Abstract:
The changes of surface coating, basic structures and mechanical proper-tie? in first stage turbine blade of GH220 alloy tested by engine rig for 236 hour? has been investigated. The results show that the structures of alloy are stable and properties of alloy still good. The isothermal treatment process at 1070℃ is suitable. It is shown that this alloy （blades） has greater potentiality.

Abstract:
The structures and mechanical properties of first - stage turbine blade of GH220 alloy tested for 700 hours by engine rig have been analyzed in detail. The results show that structures of tested blade are all stable, and the mechanical properties are still good, and the engine rig test of first stage turbine blades can be carried on.