Speculum metal metal mixtures usually contain two parts copper to one part tin along with a small amount of arsenic, although there are other mixtures containing silver, lead, or zinc. The knowledge of making very hard white high luster metal out of bronze-type high-tin alloys may date back more than 2000 years in China although it could also be an invention of western civilizations. Such metals were used in sculpture and to make more effective mirrors than the more common yellow easily tarnishing bronze mirrors. In that era mirrors of speculum metal, or any precious metal, were rare and only owned by
High entropy alloys High entropy alloys High-entropy alloys (HEAs) are substances that are constructed with equal or nearly equal quantities of five or more metals. These alloys are currently the focus of significant attention in materials science and engineering because they have potentially desirable properties. Prior to the synthesis of these substances, typical metal alloys comprised one or two major components with smaller amounts of other elements. For example, additional elements can be added to iron to improve its properties, thereby creating an iron based alloy. Hence, high entropy alloys are a novel material. Furthermore, research indicates that some HEAs have considerably better