Magnetic Properties and Microstructures of Sm–Fe–Ti Alloys With ThMn12 Structure Prepared by Melt-Spinning Method

The effects of annealing temperature (
$T_{a}$
, 600 °C–950 °C) and Sm content on the phase transformation and magnetic properties of Sm
_x
Fe
₁₁
Ti (
$x $
= 0.9, 1.0, and 1.1) alloys prepared by the melt-spinning method were investigated. In all specimens with different compositions, the crystal structure was transformed from the TbCu
₇
to ThMn
₁₂
structure as
$T_{a}$
increased. The coercivity reached 6.3 kOe in a SmFe
₁₁
Ti ribbon annealed at 850 °C. However, the grain size of this ribbon was much smaller than the critical single domain size of the SmFe
₁₁
Ti alloy. The microstructural analysis revealed that the ribbons were highly strained. To overcome the abnormal low coercivity of SmFe
₁₁
Ti alloy, precise control of the composition and removal of strain without grain growth are the critical factors.