tailieunhanh - Concise Dictionary of Materials Science Part 1

Tham khảo tài liệu 'concise dictionary of materials science part 1', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CONCISE DICTIONARY OF MATERIALS SCIENCE Structure and Characterization of Polycrystalline Materials c 2003 by CRC Press LLC A a-Al2O3 Pure alumina. Polycrystalline Al2O3 is known as corundum and single crystals as sapphire. Its crystal structure can be described as consisting of two sublattices an FCC sublattice of O2- ions and a sublattice of Al3 ions occupying two thirds of the octahedral sites in the first one. a-Fe Allotropic form of iron having BCC crystal structure and existing at temperatures below 910 C at atmospheric pressure. a isomorphous Ti system Ti-X alloy system in which the alloying element X is the a-stabilizer . it raises the temperature of the p a polymorphic transformation. a-phase in Ti alloys A solid solution of alloying elements in a-Ti. a -martensite See titanium martensite. a z-martensite See titanium martensite. a-stabilizer In physical metallurgy of Ti alloys an alloying element increasing the thermodynamic stability of a-phase and thereby raising the P a P transus in the corresponding phase diagram. In physical metallurgy of steels it is referred to as ferrite-stabilizer. a-Ti Allotropic form of titanium having a hexagonal crystal structure and existing at temperatures below 882 C at atmospheric pressure. The axial ratio of its lattice c a . a little smaller than in an ideal HCP structure. a Ti alloy Titanium alloy in which a-phase is the only phase constituent after air-cooling from the P-field in the phase diagram concerned. Alloys with a small fraction of P-phase 5 vol are usually related to the same group and are called near-a alloys. All the a alloys contain a-stabilizers. a P brass Brass with two phase constituents a copper-based substitutional solid solution a-phase and an electron compound P-phase . a P Ti alloy Alloy whose phase constituents are a- and P-phases after aircooling from the a P -field in the phase diagram concerned. Slow cooling of these alloys from the P-field results in a microstructure comprising .