热变形温度对Nd_（14）Fe_（80）B_6磁各向异性的影响

摘要

In order to investigate the effects of die-upset temperatures on magnetic anisotropy,Nd14Fe80B6 Magnets were fabricated by MPQA power hot-pressed/die-upset process,under conditions of strain 70%,4min and 850-880℃.As the deformation temperature is increased,the anisotropy is first improved,and then decreased.Die-upset at 870℃,the magnet with the ideal magnetic anisotropy,(006) texture,has been obtained,with(006) highest peak on the pattern of XRD,(004) poles relative density 130.01,I(006)/I(105) 1.88,and saturation magnetization 1.453T.If the belt-like microstructures with larger equiaxed grains are elimilated,and the angles between the local stay flaky grains and well orientated ones are narrowed,the(006) texture will be improved.If Nd2Fe14B equiaxed grains are changed to become flaky ones when the strain of whole magnet is not lower than 65%,(006) texture can be obtained,while the local rich-Nd phase is only favorable for grains to slip and the flaky ones to form.To refine their thickness will guarantee the magnet with both high coercive force,and high ratio between residual magnetization and saturation one.The average thickness of the grains in Nd14Fe80B6 die-upset at 850℃ is 76nm,and coercive force 450.6kA/m,and Mr/Ms 0.92.%在850～880℃真空热变形4min、变形量70%制备了Nd14Fe80B6各向异性磁体,实验结果表明随着热变形温度的提高,磁体的各向异性先上升后降低,870℃热变形时磁体的（006）晶面峰为X衍射图谱的主峰、（004）相对极密度最大值达到130.01、I（006）/I（105）为1.88,获得（006）磁织构,磁体的饱和磁化强度达到1.453T。如热变形过程消除平均宽度为25μm的带状组织,减少与热变形压力垂直的片状晶之间夹角为19°左右的局部片状晶,则磁体的各向异性可望进一步提高。Nd2Fe14B相在热变形过程中从等轴晶变形为片状晶,且磁体宏观变形量≥65%时,才能形成（006）磁织构,局部富稀土相只起到有利晶粒滑移、有利片状晶形成的作用。细化热变形磁体的片状晶厚度可使磁体具有高矫顽力、高剩磁与饱和磁化强度之比值。850℃热变形Nd14Fe80B6磁体的片状晶平均厚度为76nm,磁体的矫顽力为450.6kA/m,Mr/Ms为0.92。