MARTENSITE AND LIFE : DISPLACIVE TRANSFORMATIONS AS BIOLOGICAL PROCESSES

Abstract
Martensitic transformations in cylindrical protein crystals are found to perform life functions in primitive biological systems. Tailsheath contraction in T-even bacteriophages can be described as an irreversible strain-induced martensitic transformation, while polymorphic transformations in bacterial flagella appear to be stress-assisted mechanically reversible martensitic transformations exhibiting a shape memory effect. Available information indicates that the geometric, thermodynamic, and kinetic aspects of these transformations are consistent with martensitic behavior. Similar transformations involving the motion of partial (coherency) dislocations under chemical forces may underly the mechanism of motion in higher organisms as well.