MICROSTRUCTURE OF 2ND-PHASE PARTICLES IN HIGH-TEMPERATURE TI-55 ALLOYAFTER CREEP

The microstructure of the second-phase particles in the Ti-55 alloy (T i-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd) have been studied by transmission electr on microscopy. The second-phase particles present consist of a ''matri x'' (which can be either dark or bright) and some small dark blocks di spersed within this matrix. The dark blots correspond to Sn3O4 (tricli nic structure, with a = 0.486nm, b = 0.588nm and c = 0.820nm). The mat rix consists of a nanocrystalline phase with a stoichiometric Nd3Sn st ructure having a space group of Pm3m and a lattice parameter of a = 0. 344nm. (C) Elsevier Science Inc., 1996.