Metals in your smartphone have no substitutes

Shades of 60 elements that make a computer chip. intelfreepress

A few centuries ago, there were just a few widely used materials: wood, brick, iron, copper, gold and silver. Today’s material diversity is astounding. A chip in your smartphone, for instance, contains 60 different elements. Our lives are so dependent on these materials that a scarcity of a handful of elements could send us back in time by decades.

If we do ever face such scarcity, what can be done? Not a lot, according to Thomas Graedel of Yale University and his colleagues who decided to investigate the materials we rely on. He chose to restrict his analysis to metals and metalloids, which could face more critical constraints because many of them are relatively rare.

The authors’ first task was to make a comprehensive list of uses for these 62 elements. This is a surprisingly difficult task. Much of the modern use of metals happens behind closed doors of corporations, under the veil of trade secrets. Even if we can find out how certain metals are used, it may not always be possible to determine the proportions they are used in. Their compromise was to account for the use of 80% of the material that is made available each year through extraction and recycling.

The next task was to determine if there were any substitutes for these uses. But, as Graedel writes, “the best substitute for a metal in a particular use is not always readily apparent.” Elemental properties are quite unique and substitution will often reduce the performance of the product. But it can be done.

Two examples stand testament to that. In the 1970s, cobalt was commonly used in magnets. When a civil war in Zaire caused scarcity of cobalt, scientists at General Motors and elsewhere were forced to develop magnets that used no cobalt. More recently, a shortage of rhenium, which is used in superalloys for gas turbines, forced General Electric to develop alternatives that use little or no rhenium.

Graedel’s analysis of substitutes involved ploughing through scientific literature and interviewing product designers and material scientists. The results are a sobering reminder of how critical some metals are. On seeing the data, Andrea Sella of University College London said, “This is an important wake up call.”

Which metals have good substitutes and which don't. PNAS