Manufacturing of a Magnetocaloric Component by Uniaxial Pressing and Sintering of La-Fe-Co-Si Alloy Powders Produced by Gas Atomization

摘要

A La-Fe-Co-Si powder was produced by inert gas atomization and annealed to develop a high volume fraction of the magnetocaloric phase La(Fe,Co,Si)_(13). Fractions with different particle size were used to investigate die filling and sintering behavior. Since the powder is brittle and does not flow, it cannot be directly pressed into compacts with enough green strength. Consequently, it was first granulated with a binder and, afterwards, pressed into a component with a wall thickness of ～1 mm. Subsequently, the green compacts were debinded and sintered under an inert atmosphere. Due to the high affinity of lanthanum for oxygen and the high surface area of the component, a dry atmosphere with low oxygen is important for a successful sintering. Sintering cycle was optimized to keep the high volume fraction of magnetocaloric phase, along with minimum distortion. The constitutive phases were studied by X-ray diffraction and scanning electron microscopy.