Fracture properties of La(Fe,Mn,Si)13 magnetocaloric materials

TL;DR

This study develops a workflow combining microstructural analysis and mechanical testing to evaluate the fracture properties of La(Fe,Mn,Si)13 magnetocaloric alloys, aiding in ensuring their structural integrity in magnetic refrigeration devices.

Contribution

It introduces a quantitative method to assess fracture toughness and defect impact in La(Fe,Mn,Si)13 alloys, facilitating industrial quality control and device reliability.

Findings

Estimated fracture toughness KC ≈ 4 MPa m^1/2.

Residual strength curve links defects to mechanical strength.

Predictive relationship enables defect-based performance assessment.

Abstract

La(Fe,Mn,Si)13 alloys are a promising material family for magnetic refrigeration. Challenges associated with their structural integrity during device assembly and operation requires deep understanding of the mechanical properties. Here we developed a workflow to quantitatively study the fracture properties of La(Fe,Mn,Si)13 plates used in magnetic cooling devices. We employed microstructural characterisation, optical examination of defects, and four-point bending tests of samples with known defect sizes to evaluate their mechanical performance. We established the residual strength curve which directly links observed defects to mechanical strength. The estimated fracture toughness KC of hydrogenated La(Fe,Mn,Si)13 is approximately 4 MPa m^1/2 for the geometry employed. The established relationship between strength and crack length enables the prediction of mechanical performance through examination of defects via optical microscopy, therefore can be used industrially for directing plate selection to guarantee the mechanical stability of refrigeration devices.