A relatively low-density but high-strength metal that has excellent corrosion resistance as a cool solid, but not as a very hot solid or liquid. The thermal conductivity of this metal is very low, making it difficult to machine since it doesn't effectively dissipate the heat produced at the cutting tool location

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.