On The Fabrication Of ODS-cu And ODS-steel By Induction Melting And Casting

Oxide dispersion strengthened（ODS）alloys have excellent high temperature creep resistance,radiation damage resistance and corrosion resistance.This kind of alloy is an important material in the field of energy and transportation engineering,such as nuclear energy,aerospace engines and so on.Taking ODS-Cu and ODS-steel as a representative,this paper explores the preparation of ODS alloy by melting and casting.At present,the mature ODS-Cu is mainly based on the internal oxidation method,which has a complex process,long cycle,and difficult domestic industrial production.ODS steel can only be prepared by mechanical alloying,but for structural materials,the amount of steel is hundreds of kilograms or even tons.The current preparation method can not meet the needs of industrialization.In order to solve the problems of large-scale preparation,this paper systematically explored the feasibility of ODS Cu and ODS steel melting and casting preparation process,and proposed to use the melt rapid quenching technology to prepare oxygen-containing amorphous alloy as master alloy,mix it with Cu or steel,and directly prepare ODS Cu and ODS steel by induction melting.The process is simple,efficient,and can realize large-scale preparation.The organization and microstructure were characterized by metallography,XRD,and TEM.The mechanical properties were tested by hardness tester and tensile testing machine,and the composition of EPMA was analyzed and tested.Verify the feasibility of melting and casting preparation process.The main results of this paper are as follows:（1）Two kinds of master alloys(Fe₄₀Y₆₀)₉₆O₄and(Zr₇₆Fe₂₄)₉₈O₂ were designed,and oxygen-containing master alloys were prepared by melt rapid quenching technology.First,the experimental results show that(Fe₄₀Y₆₀)₉₆O₄ alloy has amorphous structure and oxide particles are dispersed on the amorphous matrix.DSC results showed that the amorphous temperature（T_x）increased with the increase of nominal oxygen content,indicating that oxygen entered the lattice structure of amorphous matrix.Second:(Zr₇₆Fe₂₄)₉₈O₂ alloy has amorphous structure,and T_x also increases with the increase of nominal oxygen content.These two alloys were used to prepare ODS Cu and ODS steel.（2）ODS alloys are prepared by direct smelting of master alloy with Cu or steel.Kilogram-scale ODS-Cu alloys were successfully prepared,and the effects of four smelting times of 19 min,22 min,31 min,and 40 min on the preparation of ODS-Cu alloys were explored.When the smelting time is less than 22 min,the smelting state is good,the melt fluidity is good,the float on the melt surface is less,and the formability after casting is good.When the smelting time is longer than 22 min,a large number of floating objects are formed on the surface of the melt,and the most floating objects are formed after 40 min of smelting.The main reason is that oxides are continuously formed in the melt,and the in-situ generated oxides continue to aggregate and grow up and float on the surface of the melt due to the long smelting time.Therefore,if the smelting time is too long,the oxide content of the sample decreases,and the smelting time is less than 22 min,and the preparation effect is better.（3）ODS-Cu performance analysis:The prepared ODS-Cu was characterized by EPMA and TEM.It was found that there are 1～10 nm dispersed oxides in the matrix.The characterization of mechanical properties shows that the yield strength of the sample aged at475℃for 2 hours is about 375 MPa,the tensile strength is about 410 MPa.Comparing the high-temperature mechanical properties,it is found that the 450℃tensile strength of Glidcop-Al25 is 190 MPa,and the high-temperature tensile strength of ODS Cu alloy prepared in this experiment is 285 MPa and 235 MPa,both higher than glidcopσ_s/σ_b it can be found that both are greater than 80%,which are higher than that of Glidcop Al25σ_s/σ_b is 75%,and the high temperature softening resistance of this experimental sample is much higher than that of Glidcop-Al25.Therefore,the feasibility of preparing ODS-Cu alloy by the simple melting process is proved.（4）ODS steel performance analysis:Oxygen containing master alloys with different compositions were mixed with CLAM steel,Fe Cr Al steel,and Fe Mn steel respectively,and the process feasibility of preparing oxide dispersion strengthened steel was explored by melting and casting method.The main experimental results and reasons are as follows:for the preparation of ODS steel alloy by induction melting,through metallographic and hardness characterization,it is found that the hardness of all the intermediate alloy steel is lower than or similar to that of the base steel,and no oxide is found in combination with the calibration of TEM bright field and electron diffraction pattern of the sample.Therefore,it may be due to the high melting point of the steel,above 1500℃,after the oxygen-containing intermediate alloy is added,Because the melt of induction melting keeps turning,the oxide originally formed floats on the surface;On the other hand,after the addition of the master alloy,the impurity elements（Ca,Si,S,P,etc.）in the steel react with the oxygen of the master alloy,and the rare earth elements,oxygen and sulfur are also easy to form compounds,and slag is formed in the melt,float on the surface.Therefore,the preparation of ODS steel by fusion casting is still under exploration.