Study of CuAlBe Shape Memory Alloy by X-Ray Diffraction

Abstract

A complete study of Ms-30°C polycrystalline CuAlBe shape memory alloy is made by X Ray diffraction using a texture goniometer equipped with a curved position sensitive detector. Austenite and martensite unit cells parameters are measured. Measured indexes and orientation of the habit plane are compared to those expected by the lattice parameters. Austenite after extrusion shows a strong fiber texture, volumic fraction of austenite and martensite are measured according to the deformation. Internal deformations of three grains of a Ms-100°C CuALBe sample are followed during their macroscopic deformation.

A Study on the Physical Properties of the Newly Calculated Phases of Cu-Al-Be Alloys by <i>ab initio</i> Calculations

“…The calculated lattice constant of the L2 1 phase is 5.712 Å and the corresponding volume of the unit cell is 186.36 Å 3 . The calculated lattice constant is in reasonable agreement with the experimental lattice constant, which is reported to in the range of 5.825 Å and 5.963 Å [3,32]. Together with the L2 1 phase, there are experimental and theoretical results from previous works on the 9R phase.…”

“…The lattice constants a, b, c, of the martensitic 9R structure were also calculated as 4.784 Å, 5.319 Å, and 3.840 Å in our work. The calculated lattice constants of the 9R martensitic phase are consistent with the experimental results [3,32]. Furthermore, the bulk modulus of the martensitic 9R phase was determined to be 120.4386 GPa and the pressure derivative of the bulk module as 4.4603.…”

Strain rate sensitivity in superelasticity

“…Numerical simulations for this alloy were performed using material parameters in Table 1 and microstructure data listed in Table 2 for CuAlBe alloy. Numerical values given in Table 2 for this alloy, come from crystallographic measurement performed by Moreau et al (1995) on the same material and from a micromechanical determination of the interaction matrix for CuAlBe SMA (Siredey et al, 1999). Like for CuZnAl case, the granular structure is described considering 100 spherical grains randomly oriented.…”

Orthorhombic lattice deformation of CuAlBe shape-memory single crystals under cyclic strain

“…lattices but, to our knowledge, they are never observed in CuAlBe alloys. In the austenite±martensite transformation, the stacking faults are parallel to the habit plane de®ned in a CuAlBe sample by a triplet close to (4,4,1) which is not a crystallographic plane (Moreau et al, 1995). For the sake of simplicity, we suppose that the stacking faults populate the (110) plane of the cubic lattice.…”

“…The modi®cation of the atomic arrangement induces either a shift and/or a broadening of the X-ray diffraction peak, or the appearance of satellite peaks. In a previous paper (Moreau et al, 1995), lattice strain was measured in large single grains of a CuAlBe polycrystalline sample. The in¯uence of the interaction between grains on the strain does not permit an exact evaluation of the lattice strain independently of the macroscopic elastic strain ®eld.…”