Pre-Transformation Lattice Strain Anisotropy and Central Peak Scattering

PRE-TRANSFORMATION LATTICE STRAIN ANISOTROPY AND CENTRAL PEAK SCATTERING 

LaTrobe University, Melbourne, Victoria 3083, Australia Department of Physics, 

Displacive lattice transformations, whieh are characterised by a diffusionless shear proeess have been extensively studied by metallurgists and physieists. In the language of the former these are referred to as martensitie, for the latter soft-mode . 

A distinguishing feature of the soft-mode martensitic transformation is the anomalous pre-transformation bdiaviour that is observed in a range of physieal and microstructural 

High-resolution dilatometric measurements have revealed the appearance of anisotropy in the cubic-phase thermal strain in the precursive temperature region for the soft-mode martensitic transformations in VaSi/ Ni-Al, In-Tl/ and SrTiOa In the case of Ni-Al and SiTiOa, the onset temperatures for the strain anisotropy are close to those at which the appearance of central peak behaviour occurs. 

It is the purpose of this paper to review briefly the thermal strain anisotropy data and to consider the implications for the central peak scattering. 

---