磁场下共析铁素体在生长中的晶体学特征

Crystallographic characteristics of eutectoid ferrite during growth under high magnetic field

采用电子背散射衍射技术(EBSD)研究12 T磁场作用下硅锰铸钢磁诱发珠光体(MIP)的形核与生长。结果表明:低转变量的相变初期,组成相之一的珠光体铁素体相(PF)主要沿着<110>//ND方向生长,具有<111>//ND和<100>//ND等其他位向所占比例相对较低,表现出一定的择优形核与生长;随着转变量的增加,初期成核的PF维持其择优晶向长大,新生相的晶体学位向除受到界面能、体积自由能以及磁自由能等的综合影响外,还将受到母相中逐渐累积的弹性应变能的限制,空间取向趋于多向化,表现为中后期形成的MIP的择优生长趋势变弱,其他取向的MIP相对比例也有所降低,失去了<110>//ND的择优性;将100%转变量的试样继续延长磁处理时间,表现为无微织构特征。

Effect of a high magnetic field( 12 T) on nucleation and growth of magnetic-induced pearlite( MIP) in Si-Mn casting steel was studied by electron back scattering diffraction( EBSD) technology. The results show that pearlite ferrite phase( PF) along with < 110> / /ND components have priority to nucleation and growth at the early stage of phase transformation,as compared with other texture components,such as < 111 > / /ND and < 100 > / /ND,which indicates PF has an obvious preferred orientation during nucleation and growth by the applied high magnetic. With the low transformed fraction of MIP increasing,the initial nucleation PF maintain its preferred crystallographic orientation to grow up,while new phase suffer not only the comprehensive influence from interfacial energy,volume free energy and the magnetic free energy,but also accumulated elastic strain energy of parent gradually,resulting in multidirectional space orientation and further losing preferred direction on < 110 > / /ND; 100 percent transformation of sample continued to extend the magnetic processing time don't perform any micro texture features.