Tin of protons. It has two main allotropes: at room temperature, the stable allotrope is β-tin, a silvery-white, malleable metal, but at low temperatures it transforms into the less dense grey α-tin, which has the diamond cubic structure. Metallic tin does not easily oxidize in air. The first tin alloy used on a large scale was bronze, made of tin and copper, from as early as 3000 BC. After 600 BC, pure metallic tin was produced. Pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper, antimony, and lead, was used for flatware from the Bronze
Beryllium copper powdered steel or iron seats & guides. The softer BeCu reduces valve wear and increases valve life. Beryllium copper (C17200 & C17300) is an age-hardening alloy which attains the highest strength of any copper base alloy. It may be age hardened after forming into springs, intricate forms or complex shapes. It is valued for spring properties, corrosion resistance, stability, conductivity, and low creep. Tempered beryllium copper is C17200 & C17300 that has been age hardened and cold drawn. No further heat treatment is necessary beyond a possible light stress relief. It is sufficiently ductile to wind on its own diameter