Please choose your delivery country and your customer group
In this paper, we present a novel process based on gas atomization and powder metallurgy techniques to produce reliable and stable (La1-zCez)(Fe1-x-yMnySix)13Hn materials, with 0.08 ≤ x ≤ 0.15, 0 ≤ y ≤ 0.05, 0 ≤ z ≤ 0.3 and 1.5 ≤ n ≤ 3. With this process, shaped pieces ready-to-use into refrigeration devices can be produced. Gas atomisation is a rapid solidification technique that prevents the La-Fe-Si-type alloy from forming very large α-Fe dendrites during cooling, allowing to easily and efficiently heat treat the obtained powder to form the magnetocaloric NaZn13-type intermetallic. In this process, a batch of 500 kg of alloy was first gas atomized into powder. The powder was then annealed at 1373 K under Ar for one hour to reach around 95% of magnetocaloric phase, and subsequently hydrogenated. Finally, the powder was shaped into composite shaped products containing 91.5 wt.% of powder, by extrusion. This process induces no loss of matter and allows producing non fragile pieces comprising thin portions. Our first results on the stability of partially hydrogenated (La,Ce)(Fe,Mn,Si)13 materials are shown and we discuss on the possible existence of conditions of instability liked to both the composition of the magnetocaloric phase and the level of hydrogenation.