Study On Mechanical Properties Of Low Density MA/ODS Nickel-Based Superalloy And Diffusion Property Of The Adding Phase

The current research development of Nickel–based superalloys at home and abroad,the development prospects and the preparation of the samples were reviewed at first. Thecomposition of phases, strengthening mechanism and the role of alloying elements weredeeply discused. The ODS nickel-based superalloy samples were made by mechanicalalloying(MA). And by adjusting the amount of nano-oxide, the milling process, powermolding technology, vacuum sintering process and electroless nickel plating technology inorder to increase the comprehensive performance of the alloys, such as relative density,tensile properties, hot corrosion resistant, the microscopic morphology of section andtensile fracture. And summed up the optimal Preparation of thelow-density ODS nickel-based superalloy.During the mechanical alloying process, the amount of added nano-Y2O3ranges from0to10wt%. The alloy powders were milled with the agate balls at different rotationalspeed(180rpm,200rpm,220rpm,300rpm,330rpm,350rpm) for48h with ball-to-powderweight ratio of20:1. Using two methods to add process control agents(PCA), one wasadding2wt%ethanol and the other was adding1wt%stearic acid(SA) during the millingprocess. Using the second method and rotational speed at220rpm can obtain flake powderwhich were benefit for subsequent molding process. The milled power were moded bylaboratory-made molding machine. The compacts could get high relative density andnon-hierarchical cracking under the pressure of550MPa for parking60s.The alloy compacts were prepared by super-solidus liquid phase sintering method atdifferent sintering temperatures(1260℃,1265℃,1285℃,1295℃,1300℃) and researchingthe effect of sintering process on the performance of the alloys. The results show thatsamples with1.5wt%Y2O3sintered at1265℃for2h could get the best performance ofwhich the relative density achieve93.18%and the tensile strength achieve689MPa whichimproved25.27%than those alloys without adding Y2O3. The Y2O3particles would easilyreunite at the grain boundaries and formed discontinuous ceramic phase which reduce theperformance when the Y2O3content increased in the samples.Hot corrosion test at800℃for20h was conducted on samples which contain different Y2O3mount(0,1.5,2,5,8,10wt%).The hot corrosion kinetics, morphology andelemental distribution of the oxide film were researched. Explaining the mechanism of hotCorrosion resistance of the matrix alloys and analyzing the effect of Y2O3on improvinghot corrosion resistance of the superalloy. The experimental results showed that amount ofnano-Y2O3can effectively increase hot corrosion resistance.The effect of surface modification of Y2O3and electroless nickel plating onmicroscopic morphology of composite powder and properties of alloys was studied. Theoptimal Y2O3adding content of samples improved by the1.5wt%to5wt%. Andcomprehensive performance of the samples sintered at1285℃for2h by electroless nickelplated increased which the relative density improve by the94.52%to98.77%and thetensile strength improve by the628Mpa to756Mpa that improved20.38%than thosesamples without electroless nickel plating.