Abstract
suggesting that the thickness of the second layer is important in the microstructural evolution. All RC and EBRC laminates showed evidence of intermetallic formation in the as deposited microstructure, in particular TiAl3, Ti3Al and TiAl. F.c.c. Ti was also identified in RC and EBRC laminates with nanometre thick Ti and Al layers. The lattice parameter of f.c.c. Ti was 0.436nm, in agreement with earlier reports. EBRC laminates with micron thick layers of Ti and Al retained the layered structure after 2 hours at 823K while the layered structure in EBRC laminate with nanometre thick layers of Ti and Al was destroyed after Imin at 573K. The latter was accompanied by the formation of TiAls with a heat of formation substantially lower than the heat of formation of TiAl3 in bulk alloys. Stresses in EBRC laminates with nanometre thick layers of Ti and Al varied from 550MPa to l.BGPa. It is suggested that these stresses play an important role in interdiffusion between the layers and that they cannot be ignored when considering the development of the microstructures of the laminates. Earlier reports that there is an enhancement of modulus and hardness in laminates with thin layers have not been confirmed in this thesis.