Anomalous ideal tensile strength of ferromagnetic Fe and Fe-rich alloys

TL;DR

This paper investigates why iron has the lowest ideal tensile strength among transition metals, revealing that magnetism and alloying effects significantly influence its strength, with implications for ferromagnetic Fe and Fe-rich alloys.

Contribution

It uncovers the magnetic origin of iron's low tensile strength and analyzes how dilute alloying elements modify its magnetic and mechanical properties.

Findings

Magnetism partly causes iron's low tensile strength.

Alloying elements alter iron's magnetic response.

Strong ferromagnetic behavior is induced by certain solutes.

Abstract

Within the same failure mode, iron has the lowest ideal tensile strength among the transition metals crystallizing in the body-centered cubic structure. Here, we demonstrate that this anomalously low strength of Fe originates partly from magnetism and is reflected in unexpected alloying effects in dilute Fe(\emph{M}) (\emph{M} = Al, V, Cr, Mn, Co, Ni) binaries. We employ the structural energy difference and the magnetic pressure to disentangle the magnetic effect on the ideal tensile strength from the chemical effect. We find that the investigated solutes strongly alter the magnetic response of the Fe host from the weak towards a stronger ferromagnetic behavior, which is explained based on single-particle band energies.