Microstructure And Properties Of 9Cr-ODS RAFM Prepared By PM

In this thesis, the article briefly introduced the development of nuclear fusion , the advantages and operating environment of the first wall structural materials, then summarize the current situation of first wall structural materials used in nuclear fusion reactor. In the experiment, prepared 9Cr-ODS RAFM steel by powder metallurgy, including MA, hydrogen annealing, compression molding and vacuum sintering. The paper analys the effect and reasons of MA process on the effect of alloying , the impact of temperature on the sintering process, and alloy high temperature oxidation resistance through high-temperature oxidation tests .The experiment sutdy the effect of the different MA factors on the 9Cr-ODSRAFM steel alloying, including the studies of milling time, Ball to Powder Weight Ratio-BPR, and Process Control Agent-PCA . It analysis the phase of the milled powder by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and observes the morphology. The results show that when the ball to powder ratio and milling speed is constant, the effect of alloying powder is better with the milling time is prolonging. when the milling time is attain, the ball reach the best. The adjunction of PCA can help to improve the extraction rate, less cold welding phenomenon, and can improve the plastic powder.The experiment explores the effect of sintering temperature on densification and Alloys, analysis and tests sintered microstructure and micro-area composition by optical microscopy (OM), energy spectrum analyzer (EDS), tensile testing machine and other equipment, and tests the tensile strength. The relative density of sintered samples, the tensile strength increased with the sintering temperature increases, when the sintering temperature is 1390℃, the values were 95.4% and 562.9MPa, 1390℃is the optimum sintering temperature. We also study the effect of addition of Si and the HIP process on properties of sintered bodies. HIP treatment can greatly improve the tensile strength (875MPa), adding Si is conducive to densification of the alloy and improving the tensile strength.Sintered at different temperatures of the alloy under isothermal oxidation at 750℃95h, analyze the oxidation kinetics, observe the oxide film thickness variation and integrity, and do the EDS analysis of oxide film composition. The results show that oxidation of the same time the oxidation of low-temperature sintering samples rapid weight gain, the oxidation rate constant of large, thick oxide film, and more defects.