Study On The Mechanical Alloying Of Fe Based Alloy Powder And The Effect Of Adding Minor Elements

In this paper,nano-oxide dispersion strengthened(ODS)steel in fusion reactors,aerospace and other extreme environments is studied,the alloy composition is optimized,and the planetary ball mill is used to fabricate Fe-(9?13)Cr?Fe-(9?13)Cr-0.25Y₂O₃?Fe-(9/13)Cr-0.25Y₂O₃-0.2Ti/Zr/Hf alloy powders.Laser particle size analyzer?X-ray diffractometer(XRD)?scanning electron microscope(SEM)and energy spectrum analyzer(EDS)are applied to analyze the microscopic morphology,mean particle size,grain size,lattice distortion,phase structure and element distribution of the alloyed powder.The influence of ball milling time,ball milling speed,process control agent and different minor elements on alloyed powder is studied.The conclusions were obtained as follows:(1)Under the same speed,as increasing of ball milling time,the process of mechanically alloyed powder can be divided into four stages:rapid crushing stage,steady stage,reunion stage and anti-reunion stage.The particle size of Fe-(9?13)Cr alloy powder and Fe-(9?13)Cr-0.25Y₂O₃alloy powder generally decrease at first,and then increases and then decreases,followed by increasing as the ball milling time goes by.As the increase of the milling time,the grain size in alloyed powder continues to decrease,and it is stabilized at 40 h,while the lattice distortion continues to increase.Therefore 40 h is the best milling time so far according to our results.(2)When the ball milling time is fixed,the mechanical alloying powder crushing phenomenon becomes more serious as the increase of the speed,the powder production rate decreases,and the contamination increases.At 260 r/min,the powder yield is higher but the mechanical alloying process slows down and the mean powder particle size is larger;at 340 r/min,the mechanically alloyed powder is obviously broken into irregular small particles,and the average powder production rate is reduced to 77.39%,and the contamination increased.Therefore,the best speed under the experimental conditions is 300 r/min.(3)When the rotation speed is 300 r/min,and the ball milling time is set to 40 h.With the increase of the content of the process control agent(ethanol)is main contribution to the morphology of the 9Cr Y mechanically alloyed powder.It makes the alloying powder into a large-particle lamellar structure.With the increase of the alcohol content,the X-ray diffraction peak is sharpen and shifted to the right,which indicates the mechanical alloying process.In the mechanical alloying process,the content of the process control agent ethanol is best controlled at 2 wt%.(4)When the speed is set at 300 r/min and no process control agent is added,with the increase of ball milling time,add the same weight of Ti,Hf,Zr elements into Fe-(9/13)Cr-0.25Y₂O₃ mechanically alloyed powder.The degree of refinement of the grain size are different related to each minor element added alloying powders.Under the experimental conditions,the use of mechanical alloying technology can successfully prepare alloyed powders containing different minor elements,and the ball milling time needs to 60 h.The Zr element has the strongest effect on powder refinement among the three elements.