Aluminum Alloys with the Addition of Reduced Deep-Sea Nodules

Alena Michalcová,Pavel Novák,Matouš Orlíček

doi:10.3390/met11030421

Abstract

An innovative way to utilize deep-sea manganese nodules is described in this paper. The manganese nodules were reduced by aluminothermy and subsequently added into aluminum as a mixture of alloying elements in their natural ratio. The microstructure and properties of aluminum alloys containing 1.2, 7.7, and 9.7 wt % of reduced nodules were studied. The alloys were formed by Al matrix and minor amounts of Al6(Fe,Mn) and Al11Fe7 intermetallic phases. The alloys containing a higher amount of reduced nodules are characterized by very good thermal stability. The obtained alloys were studied by X-ray diffraction, their microstructure was observed by scanning electron microscopy, and their local chemical composition was analyzed by energy dispersive spectrometer. The hardness of the samples was measured on the initial materials and after long-term annealing. Based on the obtained results, the aluminum alloys, with the addition of reduced deep-sea nodules, can serve as precursors for processing, e.g., by rapid solidification or hot working methods.

Highlights

The seabed is covered by a large number of minerals, the two main classes of which are biogenous and hydrogenous sediments
The manganese nodules are composed of oxides and hydroxides of Mn, Fe, Cu, Co, Ni, and other elements
The milled manganese nodules from the Clarion–Clipperton zone were reduced by a stoichiometric amount of Al

Summary

Introduction

The seabed is covered by a large number of minerals, the two main classes of which are biogenous and hydrogenous sediments. In between these two classes, there are manganese nodules, known as ferromanganese concretions. The manganese nodules are composed of oxides and hydroxides of Mn, Fe, Cu, Co, Ni, and other elements. 5 cm, and mamillated shape (roundish with small humps) This unusual shape originates from frequent overturning motions, which keep them on the very top of the seafloor. Their growth is caused by microorganisms, which reduce the cations, with limited solubility in seawater. The nodules serve as documentation on sea conditions in history but are promising raw materials [1]

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