Alignment of BiMn crystal orientation in Bi-20 at% Mn alloys by laser melting under a magnetic field

This paper presents results of preliminary work done on developing a new technique to produce magnetically aligned structure in selected regions of rapidly solidified alloys. Rapid solidification of the Bi-20 at%Mn alloy resulted in dispersion of the fine BiMn grains in the supersaturated Bi-rich matrix. Low magnetization could be achieved in the rapidly solidified specimen, as compared to the equilibrium condition. The rapidly solidified specimen when further subjected to the semi-solid processing under a magnetic filed of 4T achieved the alignment of the BiMn grains due to the magnetic anisotropy and consequently exhibited a hysterisis loop in the magnetization curve. The semisolid casting by laser melting of the rapidly solidified structure under a magnetic field of 10 T achieved the BiMn alignment in a small selected region (10 pm in diameter). The experimental results pointed out the potential of the semi-solid casting by the laser melting under a magnetic filed to fabricate the aligned structure in the desired region.