{10\bar11} Transformation Twins in Titanium

Abstract

{10\bar11} transformation twins, produced in the martensite of commercially pure titanium, have been investigated by means of transmission electron microscopy and discussed in relation to the martensitic transformation. The results are as follows: (1) The thickness of the twin is 250∼3000 Å, and the appearance of these twins is different from that of internal twins in the martensite of Fe-Ni alloys or high carbon steels. (2) (\bar1011) transformation twins have three kinds of incohorent boundaries of (12\bar31)_T, (0\bar223)_T and (11\bar20)_T. (Suffix ‘T’ means the twin lattice.) From the angles between these boundaries composing nodes, it is concluded that these boundaries must not be in thermal equilibrium, and consequently they are configurations resulting from the martensitic transformation. (3) It is deduced that the (\bar1011) twin plane has come from (\bar101)_β of the matrix, and therefore the twin plane must have played an important role of the transformation.