Grain refinement
From Biocrawler, the free encyclopedia.
Grain refinement is a set of techniques used in metallurgy to ensure that the crystallites (grains) that make up a metallic object are sufficiently small. One common technique is to induce a very small fraction of the melt to solidify at a much higher temperature than the rest; this will generate seed crystals that act as a template when the rest of the material falls to its (lower) melting temperature and begins to solidify. Since a huge number of miniscule seed crystals are present, a nearly equal number of crystallites result, and the size of any one grain is limited.
An Al-Ti intermetallic with a very high melting temperature serves this role in most titanium alloys.
TiB2 is a common grain refiner for Al alloys; however, novel refiners such as Al3Sc have been suggested.
