# Phase Structure and Magnetic Properties of Nanocrystalline ThMn12-Type (Nd1−xSmx)1.2Fe10.5Mo1.5 Alloys

## TL;DR

This paper explores substituting neodymium with samarium in a type of alloy to improve its magnetic properties without needing a nitriding process.

## Contribution

Sm substitution in ThMn12-type alloys enhances magnetic performance without nitrogenation.

## Key findings

- Sm substitution preserves the tetragonal ThMn12-type phase as the dominant matrix.
- Sm substitution increases coercivity and remanence due to enhanced magnetocrystalline anisotropy.
- Sm promotes the formation of the REFe7 phase under rapid solidification.

## Abstract

Nd-based ThMn12 alloys exhibit significant potential as rare-earth (RE)-lean permanent magnets; however, their reliance on a nitriding process imposes limitations on densification due to the thermal instability of nitrides. Herein, we investigate the substitution of Nd with Sm in nanocrystalline melt-spun (Nd1−xSmx)1.2Fe10.5Mo1.5 alloys to enhance magnetic performance without nitrogenation. The results confirm that Sm substitution preserves the tetragonal ThMn12-type phase as the dominant matrix across all alloys, ensuring structural stability. Magnetic measurements demonstrate a significant enhancement in both coercivity µ0Hc and remanence µ0Mr, attributed to the strengthened magnetocrystalline anisotropy and improved squareness of the demagnetization curves induced by Sm substitution. Furthermore, microstructural characterization indicates that Sm facilitates the preferential formation of the REFe7 phase under identical rapid solidification conditions. This work provides a strategic pathway to tailoring the magnetic properties of Nd-based ThMn12 alloys, rendering them capable of exhibiting permanent magnet behavior without nitrogenation.