Physics

Dislocation

Composite material

Dynamic recrystallization

Hot working

Deformation bands

Metallurgy

Grain size

Materials science

Alloy

Grain boundary

Nucleation

Microstructure

Thermodynamics

Journal of Material Science and Technology

We elucidate the effect of lanthanum (La) on the grain refinement of Mg-3Sn-1Mn alloy during accumulative hot rolling. The lath-shaped Mg2Sn phase in the Mg-3Sn-1Mn alloy is firstly broken and spheroidized, and then the size increases and coarsens with the increase of rolling reduction, most of Mg2Sn move from grain boundary to grain and are homogeneously distributed within the matrix. However, the plate-shaped MgSnLa compound in Mg-3Sn-1Mn-1La gradually becomes fine, spheroidized, and homogeneously distributed. The grain sizes of Mg-3Sn-1Mn and Mg-3Sn-1Mn-1La alloys become fine through dynamic recrystallization (DRX), though the grain refinement of Mg-3Sn-1Mn-1La alloy is better compared to the Mg-3Sn-1Mn alloy. A large number of uniformly distributed spherical MgSnLa compounds pin the dislocations, thus increasing the dislocation density. Hence, the driving force for DRX increases and promotes the formation of deformation bands and more twins, providing the sites for DRX nucleation and growth.

Grain refinement mechanism of Mg-3Sn-1Mn-1La alloy during accumulative hot rolling