Incommensurate modulated structure study of a Cu-Zn-Al_Zr phase

摘要

Zr was added to Cu-Zn-Al shape memory alloy as a grain refinement element. There are two new phases, Cu_50.2Zr_24.6Al_17.3Zn_7.9(at/100) (Z_1 phase) and Cu_57.4Zr_20.4Zn_10.3Al_11.9 (at/100)(Z_2 phase), in the Cu-19.0Zn-13.1Al-1.1Mn-0.3Zr(at/100) alloy. The structure of the Cu_57.4Zr_20.4Zn_10.3Al_11.9 (at/100) (Z_2) Phase is studied in detail in the present paper. The results of electron diffraction and high-resolution elec- Tron microscopy(HREM) investigations indicated a one-dimensional incommensurate modulated structure In the Z_2 phase. The average structure of the phase is base-centred orthorhombic. The systematic reflection Conditions associated with the main and satellite reflections demonstrate that the Bravais class of the Z_2 Phase is P~Cmmm_111 type in a (3+1) dimensional space for the incommensurate modulated structure.