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
Metal oxide adhesion effect or RE effect. Many mechanics theories exist on this topic. The majority of them attribute the increase in adhesion strength to the greater thermodynamic stability of the impurity element bonded with oxygen than the metal bonded to the oxygen. Inserting yttrium into nickel alloys to strengthen the oxide adhesion is an example of the reactive element effect. Dislocations are thermodynamically unstable, kinetically trapped defects. Surface dislocations often create a screw dislocation when stress is applied. In certain cases, screw dislocations can negate the nucleation energy barrier for crystal growth. The adsorption of a monolayer of gas atoms is either