Solidification in Electromagnetic Field of TiB₂-Doped Shape-Memory CuAlMn-Alloy:A Methodological Study

Liquid CuAlMn shape-memory alloy,doped with TiB₂-nanoparticles,was solidified in rotating electromagnetic(EM) field for grain refinement. The influence of the TiB_2-addition and rotating EM field on the grain-size was investigated with scanning electron microscopy.The results show that TiB_2- nanoparticles and EM field had a major impact.Specifically,the uniformly distributed TiB_2-nanoparticles acted as the heterogeneous nucleation seeds,because the minimum 2 D disregistry was calculated to be 5.28%; the dual-effect of TiB_2- particles,nucleation-seed and pinning of grain-boundary,explained the grain-size reduction in low overcooling-degree of solidification.Besides,the rotating EM field effectively suppressed the agglomeration of TiB₂-nanoparticles and prevented formation of spherical stomata defects.The addition of TiB_2- 1.0%(wt) and EM field(generated by coil-current of 120 A) decreased the average grain-size to 0.41 mm,much smaller than that solidified without EM field and without TiB_2- nanoparticles.