CREEP OF A POLYCRYSTALLINE NEAR γ-TiAl Alloy WITH A LAMELLAR MICROSTRUCTURE  

作　　者：WR. Chen J.Triantafillou J. Beddoes and L. Zhao(Dept. of Mech. & Aero. Eng.,Carleton University, Ottawa,Canada Structures, Materials & Propulsion Laboratory,National Research Council, Ottawa, Canada ) 

出　　处：《Acta Metallurgica Sinica(English Letters)》1996年第6期565-570,共6页金属学报（英文版）

摘　　要：Creep of a polycrystalline near γ-TiAl alloy in two fully lamellar conditions is presented. A lamellar structure with fine interface spacing and planar grain boundaries provides improved creep resistance. The lamellar structure with wide interface spacing and interlocked grain boundaries has <1/2 the creep life, five times the minimum strain rate and greater tertiary strain.Creep strain is accommodated by dislocation motion in soft grains, but the strain rate is controlled by hard grains. The resistance to fracture is controlled by the grain boundary morphology, with planar boundaries causing intergranular fracture.To maximize the creep resistance of near γ-TiAl with a lamellar microstructure requires narrow lamellar interface spacing and interlocked lamellae along grain boundaries.Creep of a polycrystalline near γ-TiAl alloy in two fully lamellar conditions is presented. A lamellar structure with fine interface spacing and planar grain boundaries provides improved creep resistance. The lamellar structure with wide interface spacing and interlocked grain boundaries has <1/2 the creep life, five times the minimum strain rate and greater tertiary strain.Creep strain is accommodated by dislocation motion in soft grains, but the strain rate is controlled by hard grains. The resistance to fracture is controlled by the grain boundary morphology, with planar boundaries causing intergranular fracture.To maximize the creep resistance of near γ-TiAl with a lamellar microstructure requires narrow lamellar interface spacing and interlocked lamellae along grain boundaries.

关 键 词：creep γ-TiAl TITANIUM ALUMINIDES lamellar structure 

分 类 号：TG146.23[一般工业技术—材料科学与工程]