MARTENSITE TRANSITION IN RAPIDLY SOLIDIFIED TI3AL-2NB ALLOY

The microstructure of rapidly solidified Ti3Al-2Nb alloy consists of a n ordered orthorhombic alpha(0) '' phase. In the foil samples for tran smission electron microscopy prepared by chemical thinning, the alpha( 0)('')--> beta(0) transformation took place due to the charging of hyd rogen during thinning. The beta(0) --> alpha(0)('') transition in the rapidly solidified alloy can be explained by a shape deformation mecha nism, and the beta(0)/alpha(0) '' interface (habit) plane is near to { (3) over bar 34)(beta 0) . The orientation relationships between the b eta(0)and alpha(0)('') phases are [<(11)over bar>0](beta 0) parallel t o parallel to [001]('')(alpha 0), and (1 (1) over bar O)(beta 0) boole an AND (010)(alpha 0)('') = (001)(beta 0) boolean AND (100)(alpha 0)'' = 4.6''.