No abstract

No abstract

The present study concerns a fully metallic solid-liquid composite Phase Change Material based on an Al-Sn Miscibility Gap Alloy produced by powder metallurgy, including its ballmilling, compression and further sintering heat treatment. The materials obtained by different routes display a narrow melting temperature range at about 230°C, corresponding to the phase transformation of Sn-or of Sn-rich eutectic. The microstructures obtained by this manufacturing process lead to form-stable PCMs, which can keep their shape and prevent active phase leakage in service conditions. Ball milling of metal powders as mixing technique allowed to obtain a very fine microstructure, resulting in stability of thermal response and improvement of mechanical properties. Among the investigated Al-40Sn mass% samples, the most promising were those compressed at 240°C followed by sintering at 500°C.

No abstract

Al-Sn binary system is a miscibility gap alloy consisting of an Al-rich phase and a Sn-rich phase. This system is traditionally applied in bearings and more recently found application as form-stable phase change material (PCM) exploiting solid-liquid phase transition of Sn. A careful choice of production process is required to avoid macro-segregation of the two phases, which have different densities and melting temperatures. In the present study, the additive manufacturing process known as laser powder bed fusion (LPBF) was applied to an Al-Sn alloy with 20% volume of Sn, as a rapid solidification process. The effect of process parameters on microstructure and hardness was evaluated. Moreover, feasibility and stability with thermal cycles of a lattice structure of the same alloy were experimentally investigated. An Al-Sn lattice structure could be used as container for a lower melting organic PCM (e.g., a paraffin or a fatty acid), providing high thermal diffusivity thanks to the metallic network and a “safety system” reducing thermal diffusivity if the system temperature overcomes Sn melting temperature. Even if focused on Al-Sn to be applied in thermal management systems, the study offers a contribution in view of the optimization of manufacturing processes locally involving high solidification rates and reheat cycles in other miscibility gap alloys (e.g., Fe-Cu) with similar thermal or structural applications.