ABSTRACT
One Friday afternoon in 1906, a German metallurgist, A Wilm, working on Al–4% Cu alloys, quenched1 a sample. Leaving it on his bench, on his return on the Monday morning he was surprised to find it noticeably transformed. From being ductile just after quenching, it had in the meantime become very hard. The industry of duralumins (after Düren, the town where Wilm was working) had been born, with immediate and enormous consequences, particularly in aeronautics2.
