Element 12

Starting point / motivation

Highly mechanically loaded components - especially in the space sector - are often manufactured using machining technology with a high wear of cutting and milling tools. In some cases, the cutting volume can account for up to 90% due to the fact that casting (with the need for a dedicated mould) is not an economic solution for a low number of pieces, which is typically the case in space applications.

Additive manufacturing processes enable a direct approach to cost-efficient production of a part, even if only a single unit is required. For space applications, developments in the field of light metals are mainly focused on aluminum and titanium alloys. Here magnesium alloys - and in particular also magnesium composite materials - offer a great potential for weight saving due to their high specific characteristic properties (specific strength / stiffness).

In recent years space agencies such as NASA rediscovered "again" alloys of magnesium. This is partly due to improvements in corrosion protection (by coatings), but also more and more by the need to reduce further weight in spacecrafts.

Contents and goals

The project "element 12" (magnesium is the 12th element in the periodic table) deals with the development of new magnesium alloys and composites, which are specially developed for the wire based plasma arc manufacturing process.

Methods

Appropriate alloys are first developed that are characterized by corrosion resistance, show a low flammability as well as good weldability. These alloys will be especially adapted to the high cooling rate of the plasma arc process when applying individual layers and will take advantage of the subsequent in situ heat treatment during the repeated deposition of individual layers.

The alloy development will take advantage of the know- how of the LKR and also CALPHAD methods will be used to support the alloy development. In order to finally convert these alloys into 3D components, it is necessary to initially produce wires from the novel compositions by means of an innovative approach. This is done by a direct wire extrusion process developed at the LKR.

The manufactured wires from Mg alloys and composites are used for the additive production of test coupons at RHP, which are characterized in detail with respect to the mechanical properties and the corrosion behavior.

In parallel to the development of the alloys application areas for the potential use of magnesium alloys in the space applications will being investigated. These areas include an assessment for the use in launcher systems, satellite applications as well as scientific missions or even missions to Mars.

Additionally, possibilities for applications in the "NewSpace" area will be examined. Two application areas will be identified, and test components will be manufactured by RHP followed by testing in space relevant conditions. The combination of alloy development, wire production and the subsequent additive manufacturing processes via a wire-based plasma arc process represents a process chain that has not yet been investigated so far.

Most of the activities reported in literature so far are focused on wire-based technologies with using aluminum and titanium alloys. Magnesium alloys are only sporadically manufactured using powder-based technologies. Here especially from the US there are some publications. One severe drawback when working with powders of Magnesium alloys is the fact that powders from the US are subject to import restrictions and additionally there are very high purchasing and customs costs.

The choice of alloys commercially available is also limited, Compared to the powder-based manufacturing technologies, the plasma arc technology using an alloy or even composite wire, offers significant advantages in terms of safety aspects, the achievable component size and the deposition rate.

Expected results

The successful development of new magnesium alloys and composites using wire-based manufacturing technologies, including the manufacturing of the wire, will enable to establish an Austrian value chain for the manufacturing of highly demanding aerospace components.

Coordinator

RHP-Technology

Project partner

AIT Austrian Institute of Technology LKR Leichtmetallkompetenzzentrum Ranshofen GmbH

RHP-Technology
Research and technology center
Dr. Erich Neubauer
A-2444 Seibersdorf