Cost-Effective TiAl based Materials
Because of their inherent low ductility, TiAl-based materials are difficult to fabricate, especially thin gage titanium gamma aluminide (TiAl) sheet and foil. In this paper, an innovative powder metallurgy approach for producing cost-effective thin gage TiAl sheets (with 356 mm long and 235 mm wide, and a thickness of 0.74, 1.09, 1.55, and 2.34 mm, respectively) is presented. The microstructures and tensile properties at room and elevated temperatures of the thin gage TiAl are studied. Results show that these TiAl sheets have a relatively homogenous chemistry, uniform microstructure, and acceptable mechanical properties. This work demonstrates a cost-effective method for producing both flat products (sheet/foil) and complex chunky parts of TiAl for various advanced applications including aerospace and automotive industries.
Solidification behavior of Ti5Si3 whiskers in TiAl alloys
Abstract The solidification behavior of Ti 52 Al 48 – x Si ( x =0, 0.5, 1.0, 2.0, 3.0, 6.0 at.%), Ti 52 Al 48 –3Si2M (M=Cr, V) and Ti 52 Al 48 –3Si2Cr2V at.% alloys has been studied using differential thermal analysis (DTA) and microstructure examination. The Ti 5 Si 3 phase was formed during solidification of the Si containing TiAl alloys. Two types of Ti 5 Si 3 phase were found in Ti 52 Al 48 – x Si ( x =0.5, 1.0, 2.0 at.%). The first one was formed during the L→Ti 5 Si 3 +L 1 transformation as large isolated Ti 5 Si 3 whiskers formed before primary solidification, and the second one was characterized by whiskers in a eutectic morphology resulting from the solidification of L 2 →α+Ti 5 Si 3 after the primary solidification of L 1 →β+L 2 . In contrast, the primary solidification in the Ti 52 Al 48 –3Si alloy was L 1 →α+L 2 , and a third type of Ti 5 Si 3 phase was formed by a eutectoid reaction of α→γ+Ti 5 Si 3 . The effect of Cr and V on the solidification behavior and constituents of the Ti 5 Si 3 phase were studied with distributed coefficient of Cr, V, and Si. The uniform distribution of fine Ti 5 Si 3 whiskers in the Ti 52 Al 48 –3Si2Cr2V alloy gives effective reinforcement of the matrix.
Population and Settlement
Part 1 Population distribution: world population distribution variations in world population distribution population distribution in the Highlands and Islands population distribution in Japan population distribution in Brazil. Part 2 Population growth and movement: population structure the world population explosion variations in population growth migration why do people migrate types of migration in North and West Africa West German migration populating the USSR populating Australia attitudes to population control population and natural resources. Part 3 Settlements: location of settlement settlement types settlement functions settlement patterns South Wales valley settlements the changing village. Part 4 Urbanization: million cities world urbanization rural-urban migration in the developing world urban land use inner city problems urban transport the Tyneside metro spheres of influence changing shopping habits the Dutch Randstad Lagos - a city in the developing world new and expanding towns in the UK new settlements in developing countries green belts or red bricks? Part 5 Further studies: UK population migration Kenya's population problems Sheffield Washington New Town.