A kind of method of prepared by mechanical alloy nickel-based oxide strengthened dispersion alloy
Technical field
The invention belongs to field of research of metal, the novel nickel-based oxide dispersion-strengthened of a kind of preparation (Oxide Dispersion Strengthening, ODS) method of alloy are provided especially.
Background technology
The ODS alloy is a kind of important energy high-temperature structural material, and studying maximum at present is the ODS steel.The research and development of ODS alloy are very active in Japan and America and Europe, and China also more and more pays close attention to the fundamental research in this field in recent years.
With the ODS ferritic steel is example, because it has the BCC crystalline structure, under the neutron irradiation condition of 200dpa, still have low-down void swelling rate, add excellent anti-oxidant and corrosion resistance, the ODS ferritic steel can be used for fast reactor and international IV for the clad material in the advanced reactor, first wall material and thermal structure spare.The exploitation of ODS ferritic steel is significant to the thermo-efficiency that improves reactor, the security that reduces environmental pollution, assurance reactor and long lifetime operation.In fusion reactor, the Working environment of first wall/covering is very harsh, not only requires material to have the good high-temperature creep-resistant property, but also extraordinary radioresistance injury reinforcing performance will be arranged.The working temperature of traditional ferrite/martensite steel is the highest can only to reach 550~600 ℃, and the oxide dispersion strengthening ferrite steel can be brought up to working temperature 700 ℃.The stabilized nano oxide particle has been given the high temperature creep property of material excellence.The ODS ferritic steel realizes that the key that breaks through is to utilize Y
2O
3Dissolving/separate out mechanism, usually obtain more tiny oxide compound wild phase by adding Ti unit simultaneously, and can make the distribution of wild phase in matrix more even.In ma process, Y
2O
3Particle dissolves, and separates out with the form of Y-Ti-O complex oxide (2nm) in heat-processed subsequently.Because the particle diameter (3-5nm) of the oxide particle of separating out is less than the Y that adds
2O
3Particle diameter (20-30nm).The high temperature creep property of this particle diameter to wild phase, grain fineness number, martensitic transformation and ODS ferritic steel all has crucial effects.
Nickel-base sintered superalloy can be at high-temperature oxidation resistant or anticorrosive more than 600 ℃, and high-temperature material that can long term operation under certain stress, and it is widely used as high temperature structured materials such as engine turbine disk owing to having the excellent high-temperature performance.Nickel-base sintered superalloy has solved traditional casting and has forged superalloy and cause problems such as the serious and hot workability difference of ingotism because of the alloying level height, thereby make the powder metallurgy superalloy turbine disk have more excellent mechanical property and hot workability, the nickel-base high-temperature material is brought up to a brand-new level, thereby become the preferred material of key parts such as high thrust-weight ratio aero-engine turbine disk.China is since the research of late nineteen seventies start powder superalloy, gone through two generation powder metallurgy superalloy research process, be respectively the damage tolerance type FGH96 alloy of 750 ℃ of the high strong type FGH95 alloy of 650 ℃ of first-generation use temperatures and s-generation use temperatures.Compare the high strong type FGH95 of first-generation alloy, the FGH96 alloy has following characteristics on optimizing components: [1] has added more solid solution strength Elements C o, Mo and W, the hot strength of raising alloy; [2] reduced γ ' phase forming element Al, the total amount of Ti makes γ ' phase volume percentage ratio reduce to less than 40% from 50%; [3] element nb content is reduced to 0.8% from 3.5%, the auxiliary γ ' phase volume percentage ratio that reduced of the effect first, and it two is notch sensitivities of improving alloy.In addition, the increase of Cr content can improve the oxidation-resistance of alloy, and the Ce that adds trace is to purify the highly malleablized effect of crystal boundary and raising crystal boundary.This shows that the FGH96 alloy has more excellent comprehensive mechanical properties.
The ODS nickel based super alloy still has excellent high temperature creep property, fatigue property and antioxidant property more than 1000 ℃.Can be used as turning vane or turbine blade in the turbo-jet engine, life-time service at high temperature not only, and can also bear gaseous corrosion, creep and fatigue loading.The high temperature creep property of ODS nickel based super alloy excellence mainly has benefited from dispersion-strengthened, the γ ' [Ni of oxide particle
3(Al, Ti)] precipitation strength and elongate crystal grain and suppress the crystal boundary slippage.The middle temperature of ODS nickel based super alloy (700~900 ℃) strength ratio Ni-based cast superalloy is low, and the interpolation by Al, Ti and Ta has formed FCC (L1
2) ordered structure γ ' phase and keep coherence with the γ matrix, improved medium temperature intensity.When used (T>1000 ℃) under higher temperature, γ ' was because dissolving loses strengthening effect, and the strengthening effect of steady oxide at this moment accounts for leading.At present, the problem of ODS nickel based super alloy existence is that (15~50nm) than the Y in the iron-based ODS alloy for the particle diameter of dispersed oxide phase
2Ti
2O
7Disperse phase (3nm) is slightly much bigger, and this is because Y
2O
3Al reaction easy and solid solution forms a series of Y-Al-O complex oxide (Al
2Y
4O
9, Al
5Y
3O
12And AlYO
3), and a small amount of Al
2O
3And the generation alligatoring.Therefore, the particle diameter of managing to reduce oxide compound is the key point that guarantees long-term structure stability and further improve mechanical property.
Summary of the invention
The ODS alloy that the objective of the invention is development of new by γ ' phase and the common reinforcement of oxide compound.This method can prepare nano oxide dispersion phase enhanced metal-base composites, has that disperse phase is evenly distributed, the strengthening effect outstanding feature.
The present invention intends by adding Y based on the composition (as shown in table 1) of FGH96 alloy
2O
3Further improve the high temperature creep property of alloy.The Hf energy and the Y that add
2O
3In conjunction with also forming more stable Y
2H
2O
7Complex oxide keeps coherence or half coherence with matrix, and disperse phase is played the effect of refinement, and this will make strengthening effect strengthen.
The present invention adopts high-energy ball milling with Y
2O
3Uniform particles is dispersed in the matrix, then by the heat and other static pressuring processes densification.Y
2O
3Be the most effective strengthening phase, this is because it has and dissolves/separate out mechanism.In ma process, Y
2O
3Particle dissolves, and in the process of postheating with Y-Hf-O, the form of complex oxides such as Y-Al-O is separated out, and makes the particle diameter of the oxide particle of separating out just might be less than the Y of original interpolation
2O
3Particle diameter, this just lays a good foundation for the raising of high temperature creep property.The technical process of novel Ni-based ODS alloy is as shown in Figure 1:
The chemical ingredients (weight %) of table 1FGH96 alloy
At first with Co, Cr, Mo, W, Al, Ti, Nb, B, Zr, C and Ni according to the composition proportion weighing shown in the table 1, add the oxide particle (Y of 0.8~1.5 weight % then in addition
2O
3) and the oxide compound refinement element (Hf) of 1~3 weight %.The Hf element is the crucial alloying element of refinement disperse phase, type, particle diameter and distributing homogeneity that the addition of Hf element can better controlled dispersed oxide phase in the scope of 1~3 weight % the time.Wherein the massfraction of Hf element is in 1.2~1.8% the scope time, and it is to thinning effect the best of disperse phase.Then, this element mixed powder encapsulates in glove box, and protective atmosphere is a high-purity argon gas.By high-energy ball milling with Y
2O
3Uniform particles is dispersed in the Ni substrate; Powder coheres on the ball grinder inwall in the high-energy ball milling process to avoid as process control agent to add 1-3 weight % stearic acid.The rotating speed of ball mill and enough ball milling time be the oxide compound homodisperse and in matrix the dissolved key parameter, the rotating speed of ball mill is controlled in 380~500 rev/mins the scope, the ball milling time is 36-72 hour.Powdered alloy behind the high-energy ball milling carries out vacuum canning with soft steel, carries out densification then on hot isostatic pressing, and temperature is 950~1200 ℃ and is incubated 3 hours, can guarantee that so obvious alligatoring does not take place crystal grain and oxide compound is grown up.The fine and close sample that obtains behind the hot isostatic pressing carries out solution heat treatment at 950~1200 ℃, carries out ageing treatment at 600~900 ℃ at last, and this just obtains novel Ni-based ODS alloy.Figure 2 shows that through the SEM microstructure after solid solution and the timeliness thermal treatment, visible γ ' phase particle diameter tiny and in matrix uniform distribution.Figure 3 shows that the TEM microstructure of novel Ni-based ODS alloy, nano level oxide particle is evenly distributed in the matrix.The volume fraction of γ ' phase, particle diameter and size distribution are controlled by the change of suitable solution treatment, ageing treatment and rate of cooling easily.Optimize Y
2O
3Content can change the strengthening effect of dispersed oxide phase, thereby reach the requirement that improves high temperature creep property.A key of this novel Ni-based ODS alloy is to adopt the interpolation of Hf element to come the disperse of refinement oxide compound is distributed, reduce particle diameter and dwindled average headway between the particle, according to the dispersion-strengthened theory, this motion to effective pinning dislocation under the high temperature will be played more effective effect.
Advantage of the present invention is the characteristics of two kinds of strengthening phases of comprehensive utilization: γ ' (700~900 ℃) strengthening effect in intermediate temperature range is more remarkable, Y
2O
3Also has good reinforced effects Deng nano-oxide during greater than 1000 ℃ in temperature.The two has complementarity, they is combined can give play to the mechanical behavior under high temperature of nickel-base alloy to greatest extent.In addition, owing to adopted nickel-base alloy FGH96, help improving fatigue property and damage tolerance performance as basic ingredient with excellent comprehensive mechanical properties.γ ' phase separate out pattern, volume fraction is regulated by thermal treatment process easily, and has the more sophisticated technology can be for reference.Adopt special alloying element Hf that dispersed oxide is played effective refining effect mutually, this will increase substantially its strengthening effect.This novel Ni-based ODS alloy is expected to life-time service at high temperature, and can also bear gaseous corrosion, creep and fatigue loading, in high-temperature material fields such as turbine engine blades good application prospects is arranged.
Description of drawings
Fig. 1 is a process flow sheet of the present invention
Fig. 2 is the pattern of γ ' phase in the novel Ni-based ODS alloy
Fig. 3 is a nano-oxide particles in the novel Ni-based ODS alloy
Embodiment
Comparison example 1: the novel Ni-based ODS alloy that no Hf element adds.
At first Ni-13 weight %Co-15 weight %Cr-4 weight %Mo-4 weight %W-2.2 weight %Al-3.7 weight %Ti-0.8 weight %Nb-0.03 weight %C is carried out weighing according to composition proportion, the particle diameter that adds 1 weight % then is the oxide particle (Y of 20~30nm
2O
3) and the oxide compound refinement element (Hf) of 0 weight %.Then, this element mixed powder encapsulates in glove box, adopts high-purity argon gas (99.999%) as protective atmosphere.By mechanical alloying with Y
2O
3Uniform particles is dispersed in Ni substrate; Powder coheres on the ball grinder inwall in the high-energy ball milling process to avoid as process control agent to add the stearic acid of 1.5 weight % simultaneously.The rotating speed of ball mill is 400 rev/mins, and the ball milling time is 48 hours.Powdered alloy behind the high-energy ball milling carries out vacuum canning with soft steel, carries out densification then on hot isostatic apparatus, and hip temperature is 1050 ℃ and is incubated 3 hours.The fine and close sample that obtains behind the hot isostatic pressing carries out solution heat treatment (shrend) at 960 ℃, carries out timeliness thermal treatment at 760 ℃ at last, and this just obtains novel Ni-based ODS alloy.The volume fraction of γ ' phase is 38%, and the median size of γ ' phase is 1.5 μ m, and the mean sizes of oxide compound is 39nm.
Embodiment 1: the novel Ni-based ODS alloy that adds 1.5 weight %Hf elements.
At first Ni-13 weight %Co-15 weight %Cr-4 weight %Mo-4 weight %W-2.2 weight %Al-3.7 weight %Ti-0.8 weight %Nb-0.03 weight %C is carried out weighing according to composition proportion, the particle diameter that adds 1 weight % then is the oxide particle (Y of 20~30nm
2O
3) and the oxide compound refinement element (Hf) of 1.5 weight %.Then, this element mixed powder encapsulates in glove box, adopts high-purity helium (99.999%) as protective atmosphere.By mechanical alloying with Y
2O
3Uniform particles is dispersed in Ni substrate; Powder coheres on the ball grinder inwall in the high-energy ball milling process to avoid as process control agent to add the stearic acid of 2 weight % simultaneously.The rotating speed of ball mill is 400 rev/mins, and the ball milling time is 48 hours.Powdered alloy behind the high-energy ball milling carries out vacuum canning with soft steel, carries out densification then on hot isostatic apparatus, and hip temperature is 1050 ℃ and is incubated 3 hours.The fine and close sample that obtains behind the hot isostatic pressing 1150 ℃ carry out solution heat treatment and with 25 ℃/minute rate of cooling slow cooling to room temperature, carry out timeliness thermal treatment at 760 ℃ at last, this just obtains novel Ni-based ODS alloy.The volume fraction of γ ' phase is 37%, and the median size of γ ' phase is 230nm, and the median size of oxide compound is 11nm.
Embodiment 2: the novel Ni-based ODS alloy of inferior solid solution+slow cooling thermal treatment (25 ℃/minute) preparation.
At first Ni-13 weight %Co-15 weight %Cr-4 weight %Mo-4 weight %W-2.2 weight %Al-3.7 weight %Ti-0.8 weight %Nb-0.03 weight %C is carried out weighing according to composition proportion, the particle diameter that adds 1 weight % then is the oxide particle (Y of 20~30nm
2O
3) and the oxide compound refinement element (Hf) of 1.5 weight %.Then, this element mixed powder encapsulates in glove box, adopts high-purity argon gas (99.999%) as protective atmosphere.By mechanical alloying with Y
2O
3Uniform particles is dispersed in Ni substrate; Powder coheres on the ball grinder inwall in the high-energy ball milling process to avoid as process control agent to add the stearic acid of 1 weight % simultaneously.The rotating speed of ball mill is 400 rev/mins, and the ball milling time is 60 hours.Powdered alloy behind the high-energy ball milling carries out vacuum canning with soft steel, carries out densification then on hot isostatic apparatus, and hip temperature is 1050 ℃ and is incubated 3 hours.The fine and close sample that obtains behind the hot isostatic pressing carries out solution heat treatment (rate of cooling is 25 ℃/minute) at 1150 ℃, carries out timeliness thermal treatment at 760 ℃ at last, and this just obtains novel Ni-based ODS alloy.The volume fraction of γ ' phase is 45%, and the median size of γ ' phase is 1.2 μ m, and the median size of oxide compound is 10nm.
Embodiment 3: the novel Ni-based ODS alloy of crossing solid solution+fast cold and hot processing (800 ℃/minute) preparation.
At first Ni-13 weight %Co-15 weight %Cr-4 weight %Mo-4 weight %W-2.2 weight %Al-3.7 weight %Ti-0.8 weight %Nb-0.03 weight %C is carried out weighing according to composition proportion, the particle diameter that adds 1 weight % then is the oxide particle (Y of 20~30nm
2O
3) and the oxide compound refinement element (Hf) of 1.5 weight %.Then, this element mixed powder encapsulates in glove box, adopts high-purity argon gas (99.999%) as protective atmosphere.By mechanical alloying with Y
2O
3Uniform particles is dispersed in Ni substrate; Powder coheres on the ball grinder inwall in the high-energy ball milling process to avoid as process control agent to add the stearic acid of 3 weight % simultaneously.The rotating speed of ball mill is 400 rev/mins, and the ball milling time is 72 hours.Powdered alloy behind the high-energy ball milling carries out vacuum canning with soft steel, carries out densification then on hot isostatic apparatus, and hip temperature is 1050 ℃ and is incubated 3 hours.The fine and close sample that obtains behind the hot isostatic pressing carries out solution heat treatment at 1150 ℃, and controlled chilling speed carries out timeliness thermal treatment at 760 ℃ at last with 800 ℃ of/minute cool to room temperature, and this just obtains novel Ni-based ODS alloy.The volume fraction of γ ' phase is 41%, and the median size of γ ' phase is 0.8 μ m, and the median size of oxide compound is 9nm.