摘要
To take the advantage of gadolinium(Gd) in developing and manufacturing RE-permanent magnets,the magnetic properties and phase precipitation behavior of Gd_(2)Fe_(14)B alloys prepared by melt spinning were investigated in this work.The results show that optimally direct quenched nanocrystalline Gd_(2)Fe_(14)B alloy exhibits the magnetic properties with remanence J_(r) of 0.51 T,coercivity H_(c) of 187 kA/m,and maximum energy product(BH)_(max) of 33.1 kJ/m^(3).It also shows excellent thermal stability with a small negative temperature coefficient of J_(r)(α=-0.066%/K) and a positive temperature coefficient of H_(c)(β=0.171 %/K).The phase precipitations of as spun Gd_(2)Fe_(14)B alloy during melt spinning and over-quenched amorphous Gd_(2)Fe_(14)B alloy during heat treatment were clarified.The magnetic properties of the crystallized alloys annealed at 800℃ are close to those of the optimized directly quenched as-spun alloys,indicating good performance stability under various processes.In addition,the role of Gd substitution in(Y_(1-x)Gd_(x))_(2)Fe_(14)B alloys was systematically studied.Gd substitution can significantly enhance the thermal stability and decrease the irreve rsible remanence loss of Y_(2)Fe_(14)B alloy.With increasing Gd conte nt,Gd-doped Y_(2)Fe_(14)B alloys show continuous enhancement of H_(c) at elevated temperatures.The highest β value of 0.22%/K was obtained in(Y_(0.2)Gd_(0.8))_(2)Fe_(14)B alloy at 300—400 K.Gd substitution is not only effective in improving the exchange coupling effect and corrosion resistance of Y_(2)Fe_(14)B alloy but also superior to Nd in terms of improving the oxidation resistance.The present work has certain instructions for designing and developing new low cost RE permanent magnets with improved thermal and environment stability.
基金
Project supported by the National Natural Science Foundation of China (52071143,U21A2052)。
