Experimental analysis of thermomechanical properties of innovative metal matrix composites processed by Additive Manufacturing for space rocket applications.

The aerospace industry is constantly looking for innovative materials with high thermal conductivity and high resistance with which to produce liquid rocket engines. In this context, additive manufacturing is widely used: SLM (Selective Laser Melting) is an additive manufacturing technique which processes the parts by melting metallic powders with a laser. Sophia High Tech srl has patented a powder mixing process through which it is possible to obtain an innovative metal-matrix composite starting from copper (65%) and 17-4PH (35%) powders: Cu174PH processable by SLM. The aim of this thesis work is to analyse the effects of heat treatments on properties and microstructure of Cu174PH and to optimizing the best compromise in terms of thermal and mechanical properties. For this purpose, 7 different heat treatments were carried out on 7 specimens. Mechanical and thermal tests such as hardness tests, thermal conductivity tests and CT scans were then carried out. From these first analyses, the 3 best heat treatments were identified to plan a new extended testing campaign. The influence of heat treatments on the material in terms of micrographic and chemical properties was also investigated. Micrographic tests, EDS chemical analysis and fractographic tests were carried out via SEM. Finally, the starting powder was analysed via SEM and optical microscope. It has therefore been shown that heat treatments bring a benefit to the material in terms of thermal and mechanical properties and an indication has been given of which treatments lead to the best properties.