Microstructure and Properties of Natural Alloy Prepared by Aluminothermic Reduction of Deep-Sea Nodules and Processed by Rapid Solidification

Abstract

This paper explores the investigation of a natural alloy processed using the rapid solidification technique. The study involves the reduction of manganese nodules through aluminothermy with a 20 wt. % excess of aluminum, followed by further processing of the resulting alloy using the melt-spinning process. The obtained melt-spun ribbons were subjected to a comprehensive analysis, including X-ray diffraction, scanning electron microscopy for microstructure observation, and EDS analysis for local chemical composition. The research unveiled that the rapidly solidified ribbons consist of several key phases, including β-Mn, the Heusler phase Mn2FeSi, and an intermetallic phase (Cu,Mn)3(Al,Si). Importantly, the phase composition exhibited notable differences from that of the as-reduced alloy, with a reduced number of phases in the rapidly solidified ribbons. Notably, the phase composition remained stable even after annealing, demonstrating the robustness of the rapidly solidified material. Impressively, the material exhibited a remarkable hardness of approximately 800 HV 0.1, even after 100 hours of annealing at temperatures of 500 and 750°C.