快淬SmFe合金相结构及显微组织研究

Phase Structure and Microstructure of Melt-Spun SmFe Alloys

采用快淬法制备SmFe合金的过程中,在不同快淬速率下会得到4种不同外部形貌的合金,采用XRD,SEM,EDS等方法分析不同快淬速率下SmFe合金的相组成及显微组织结构,研究快淬速率及Sm含量对快淬态合金薄带相组成和显微组织结构的影响。研究表明:随着快淬速率的升高,冷却速度及过冷度也随之升高,合金薄带的相组成与组织形貌发生较大的改变,当快淬速率达到15 m·s-1时,SmFe合金的相结构开始由Th2Zn17型晶体结构转变为TbCu7型结构,通过对不同快淬速率下获得的合金薄带进行SEM和EDS分析,确定快淬态的SmFe合金薄带均由α-Fe枝晶相、包晶SmFe相及富Sm相组成,并且随着快淬速率的升高,枝晶逐渐向等轴晶转变,晶粒得到一定程度的细化,当快淬速率达到40 m·s-1时,枝晶生长转变为球状晶生长,晶粒大幅度细化,同时偏析现象消失,组织分布均匀化;通过对在同一快淬速率下获得的不同Sm含量的快淬SmFe合金薄带进行XRD分析,发现Sm含量的降低有利于TbCu7型结构的SmFe合金的获得,经SEM与EDS分析,发现随着Sm含量的增多,合金组织中α-Fe枝晶相逐渐减少,富Sm相逐渐增多。

Four different morphologies of SmFe alloys prepared by rapid quenching process under different quenching velocity were studied,and the effect of quenching velocity and Sm content on the phase compositions and microstructure of quenched Sm-Fe alloys were studied by XRD,SEM and EDS.The result showed that there were large differences in microstructure and phase compositions under the different quenching rate because cooling rate and undercooling would increase with the increase of quenching velocity,and when quenching rate was above 15 m · s-1,the Th2Zn17-type structure was changed into TbCu7-type structure.The products obtained at different quenching velocity were analyzed by SEM and EDS,and it was found that quenched Sm-Fe alloy was composed of α-Fe dendrites,Sm-rich and peritectic Sm-Fe phase.With the increase of quenching velocity,dendrites were transformed into equiaxed grain,and grains were refined,and when quenching rate was at 40 m · s-1,grains were refined largely and the distribution of microstructure uniformed with the disappearance of segregation phenomena.The XRD and SEM results of the alloys with different Sm content obtained at the same quenching velocity showed that the decrease of Sm content was beneficial to obtain Sm-Fe alloys with TbCu7-type and with the increase of Sm content,α-Fe dendrites were gradually decreased and Sm-rich phase were increased.