The world’s most wear-resistant alloy consists of platinum and gold

Although to the general public metals are most durable materials, engineers know that this is not the case. Without specialised coatings or lubricants, wear, deformation and corrosion inevitably follows when metal moves directly against metal.

Engineers at Sandia National Laboratories in Albuquerque, New Mexico have been studying this problem, and a new approach to the mechanics of frictional wear has led them to develop an alloy of platinum and gold which, they believe, is the world’s most wear-resistant metal as it is more durable than high-strength steel and in the same class as diamond and sapphire. They describe their work in a paper in Advanced Materials.

In general, wear resistance is believed to be related to hardness. However, the Sandia team, led by Nic Argibay and Michael Chandross, proposed a new theory stating that wear is related to how metals react to heat. Using computer simulations to calculate how individual atoms were affecting large-scale properties of the material, in particular how they affected the stability of the nanocrystalline structure of the alloy, they chose a mixture of 90 per cent platinum with 10 per cent gold. Although expensive, these metals have the advantage of being “noble” – that is, far less reactive than other metals and therefore available in very high purity with no need to worry about oxide formation.