• Santos, Hmc
• Viana, F.
• Duarte, A.
• Vieira, Mf

Abstract

Gamma titanium aluminide is an important candidate to several applications in the aerospace and automotive industries. The great-drawback of these alloys is its low ductility at room temperature. This work is part,of a study that intends to increase the ductility of gamma titanium aluminide through the addition of alloying elements. In this paper the effects of the heat treatment and the deformation processing on the microstructure of a Ti 49.5Al 1.25Ag are described. The alloy was produced by arc melting, under an argon atmosphere, using a water-cooled copper crucible. The as-cast samples were heat treated at 1300 and 1400degreesC. Encapsulated samples were deformed by double forging and multiple step rolling. The as-cast gamma-TiAl alloy presented an extended degree of segregation, have been detected three microconstituents: lamellar dendrites, interdendritic Al enriched gamma-phase and a number of Ag rich particles located at the dendritic/interdendritic interface. The heat treatment at 1400degreesC for 6 hours allowed the elimination of the as-cast microstructure and its replacement by a fully lamellar one. The thermornechanical processing produced non-homogenous microstructures of deformed lamellar grains and recrystallized gamma grains. The microstructure changes, occurring during the several stages of the processing were characterized using optical and scanning electron microscopy. The modification of the chemical composition of the phases was determined using SEM-EDS facilities.

Topics

• impedance spectroscopy
• grain
• phase
• scanning electron microscopy
• chemical composition
• copper
• titanium
• Energy-dispersive X-ray spectroscopy
• ductility
• forging
• aluminide