Magnetocaloric La(Fe,Si)13: in-situ experiments and fatigue behavior

Household refrigeration and industrial cooling applications are responsible for more than 15% of total electric energy consumption worldwide. Magnetocaloric cooling is a potential alternative  to conventional compression based technologies: this technology is expected to offer significant energy savings while at the same time the use of harmful, ozone-depleting gases is eliminated, since refrigeration is realized by a magnetic solid-state material. Here, La-Fe-Si based alloys present a promising material candidate, because of their excellent magnetocaloric properties, a comparatively low material price and Curie temperatures that can be tuned by varying the alloying components. In magnetocaloric La(Fe,Si)13, an isostructural transition with change of unit cell volume occurs at the critical temperature Tt. We use in- and ex-situ 3D computed tomography and X-ray diffraction to study this magnetovolume transition, which is the origin of the large magnetocaloric effect in this material. However, due to its brittleness, the intermetallic La(Fe,Si)13 phase is prone to cracking under magnetic or thermal field cycling. Composites from La(Fe,Si)13  powder in ductile matrices offer a solution to enhance cycling stability but reduce the effective magnetocaloric properties. Therefore, our aim is to understand the fatigue behavior by in-situ experiments and  to exploit mechanical properties of the minority phases present in this material to tailor magnetocaloric materials towards application.

Institution: 

Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research, Dresden, Germany

Date: 
Friday, March 11, 2016 - 11:00
Speaker: 
Dr. Maria Krautz und Dr. Anja Waske