Formation of face-centered cubic titanium in laser surface re-melted commercially pure titanium plate

Micron-scale face-centered cubic titanium phase (named as delta phase) were noticed in the re-melted zone of laser surface re-melted commercially pure titanium plate. The morphology, sub-structure, orientation and distribution of delta phase were investigated by scanning electron microscopy, electron back-scattered diffraction and transmission electron microscopy. Three kind formation processes of delta phase were put forward based on the investigation. The first one is alpha' -> delta transformation which takes place in single alpha' grains and leads to the orientation relationship {001}delta//{0001}alpha'<110>delta//<11<(2)over bar>0>alpha'. The second one is beta > alpha' + delta transformation which takes place at alpha'/alpha' interfaces and leads to the orientation relationship{001}delta//{1 (1) over bar0}beta<110>delta//< 111 > beta. The third one is another kind of beta -> alpha' + delta transformation that takesplace at alpha/alpha' interfaces and leads to the orientation relationship {1 (1) over bar1}delta//{1 (1) over bar0}beta<110>delta//<111 alpha' transformation acts as the assistant driving force for the formation of delta phase. (C) 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.