Atomic ordering in CuZnAl shape memory alloys investigated via x-ray absorption and diffraction

We investigate the structure of the austenite phase in CuZnAl shape memory alloys by a combined x-ray absorption and diffraction analysis. Ab initio simulations of the near Zn-edge x-ray absorption coefficient allow us to directly discard the hypothesis of a DO3 superstructure. At the same time, we give evidence of the existence of an ordered structure (B2-like) different from the L2(1) one recently proposed by neutron diffraction. However, some partial L2(1) ordering is present at room temperature. This superstructure develops and recovers order when increasing the temperature above 400 K. (C) 2008 American Institute of Physics.