Earliest records show a spoon shaped compass made of lodestone or magnetite ore, referred to as a "South-pointer" dating back to sometime during the Han Dynasty (2nd century BCE to 2nd century CE).

Optimisation des alliages : Mener des recherches approfondies sur la conception de la composition des alliages et les processus de traitement thermique pour les alliages de cuivre à haute résistance ...