Issue: Mar 2018

Advanced aluminum set to gain traction

by Richard Collins, IDTechEx

Dr Richard Collins, IDTechEX

Lightweight metals are forecast to enter a growth phase as both material maturity and market drivers become aligned. IDTechEx has released a new technical report on this topic, Lightweight Metals 2018-2028: Forecasts, developments, players, which provides extensive coverage of this field based on analyst-led primary research.
There is no material more central to this topic than aluminum. As extruded, rolled, or cast parts aluminum is penetrating all sectors, but if anyone assumes that the technological advancements have plateaued, then they could be about to miss some of the largest changes the industry has seen in recent years. One of the keys to these advancements involve the uptake of alternative alloying metals: lithium, scandium, and beryllium.
The world of aluminum alloys is not a closed book. There are minor advancements being made with minimal sub-percentile composition alterations, age hardening, and melt conditioning processes, but the largest change is set to come from looking to alternate alloying metals. Those of note include lithium, scandium, and beryllium, with each one being discussed below.
Lithium is used in small percentages with aluminum to great effect. Improvements of fatigue crack and corrosion resistance, as well as enhanced specific strength and stiffness are observed, and the market is just at the start of a significant growth period. This expected growth has been brought upon by some significant investments and from announcements in the aerospace sector.
Alcoa (now operating as a separate division called Arconic) invested in a new plant in Indiana, USA, that is claimed to be able to produce 20,000 tons of Al-Li alloy annually and Constellium has also increased is capacity with a facility in Issoire, France, with a reported capacity of 14,000 ton.
These not insignificant investments have been with a view to the upcoming industry demand. Already small amounts of Al-Li alloy is used in the A380, A350, 787 and G650, but this percentage will increase dramatically for the next-generation aircraft, the main headline is that this material is set to be used as the fuselage for the Boeing 777X series.
Despite this uptake, this alloy is not without a looming problem. Due to the large demand for lithium-ion batteries the cost for lithium metal is escalating. This price increase puts more pressure on the industries to improve the buy-to-fly ratios and increase the amount recycled. It will certainly hinder the rate that this advanced material enters industries.
The significance this metal could have on a multitude of industries is not spoken about enough. It has been said that if you had to choose one metal to alloy with aluminum it would be scandium. The properties are extensive, but relevant to this article and report is the role it plays in alloying with aluminum through the beneficial formation of cuboid microstructures (see image). Scandium provides an improved tensile strength and crucially a reduction in crack formation and improved strength of welds.
The problem has always been the price-tag. Scandium is not directly mined, but is rather a by-product of other mined material. This is about to change, as there is a number of proposed mining projects current seeking permission, raising funds, and completing feasibility studies. If they were all to become operational the annual output of scandium oxide (the precursor) would increase more than 20-fold and the price could drop from $2,500/kg to $1,500/kg.
Al-Sc alloys also have a large amount of potential for the 3D printing of metals, Airbus Group Innovation has developed and patented an aluminum-magnesium-scandium alloy called Scalmalloy. This has already been used to make innovative brackets, motorbikes, and a bionic partition.
Beryllium has strength and stiffness-to-weight properties better than all other lightweight metals, but it will not have the same impact as the other alloying metals. When used in a high percentage (ca. 60+ vol%) the effects on temperature stability and coefficient of thermal expansion of aluminum, coupled with the lightweight advantages, gives it some market opportunity.
The main applications are in precision avionic electronics and communication devices. IBC Advanced Alloys and Materion are leading this sector and have both developed castable solutions to make lower cost near-net shape and reduce the wastage, even at the expense of some of the specific stiffness. A powder metallurgy process is currently the most used for this material.
Challenges that will not go away are health and safety implications, and a scarcity of raw material that results in an intimidating price-tag, which makes it uneconomical in markets.
There are also opportunities for emerging metal matrix composites (MMCs) that possess a similar blend of properties at a lower price point to take away some of this market from beryllium. These are investigated in detail in the report.

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