Scandium, like other metals alloyed with aluminum, imparts strength and desirable
properties to aluminum, and does so in some measure to each of the eight alloy
families (Series). Scandium additions generate strength by promoting a smaller,
even-sized grain structure in alloys during solidification. Scandium shows better
strength response in some alloy families than others, but almost always with quite
small additions – between 0.1% and 0.45% Sc.
STRENGTH MATTERS FIRST
Strength is undoubtedly the single most important determinant in alloy selection for a particular manufactured
part or application. Strength determines design, weight, and often defines the manufacturing process required
to form a particular part on the manufacturing floor. Virtually all high strength alloys achieve their strength with
careful heat treatments, once in final form, which adds both cost and the potential for process failure through
unsuccessful grain refinement/repair or non-correctable deformation of finished parts.
Strength is achieved by
controlling grain growth
, keeping metal grain size small, and relieving internal stresses in the microstructure.
Scandium is excellent at this
, by promoting a small, equiaxed grain structure, and doing so in the natural
solidification process – rather than requiring complex and specific heat treatments post manufacture.
OTHER METAL PROPERTIES MATTER TOO
Other measurable properties also play a key role in aluminum alloy application, affecting usability and alloy
price. Alloy properties are what determine tolerance to harsh operating environments, damage resistance, life-
cycle estimates, weldability, and overall performance. They also determine (or dictate) specific manufacturing
techniques, to achieve part designs and meet production cost targets. Alloy properties translate either into
direct part build cost – or cost savings – on the manufacturing shop floor. In short-they significantly influence the
fit-for-purpose selection process. Therefore,
once minimum strength requirements are met for a given design,
the alloy selection process then becomes one of preserving the greatest number of usable properties
, or
sometimes, simply finding the alloy that can meet the essential property requirement for a particular application.
Scandium alloys are fully recyclable, and won’t pollute recycle streams if combined with other alloys – although it
may make economic sense to segregate based on value