METHOD OF TREATMENT OF CAST HYPEREUTECTOID ALLOYS ON BASE OF TITANIUM ALUMINIDES γ-TiAl AND αTlAl Russian patent published in 2003 - IPC

FIELD: plastic metal working; manufacture of blanks, semi-finished items and articles with specified structure. SUBSTANCE: method of treatment of cast hypereutectoid alloys on base of titanium aluminides γ-TiAl and α₂Tl₃Al includes heating and deformation performed at two stages; at first stage, deformation of blank is performed at temperature of γ-TiAl, where α₂Ti₃Al is eutectoid temperature; T_e÷T_e+ΔT^°C is selected from condition of retaining globular component of structure obtained in the course of deformation, at cooling after deformation; rate of deformation T_e - is selected in interval of ΔT whose upper limit is limited by deformability of alloy and lower limit is limited by condition of prevailing of recrystallization/globularization processes as compared with return processes; degree of deformation ε′1

is so selected that medium size of grains/colonies in blank decreases to magnitudes causing reduction of friable- brittle transient temperature ε′lmin-ε′lmax of blank to ∈₁ at temperature and rate of deformation selected within said intervals; at second stage, deformation is performed under isothermal conditions at temperature within T^*, where T^*<T_e, is minimum temperature at which deformation takes place without rupture at degree of deformation of T_min-T°eC and rate of deformation of T_min which are selected on the condition of obtaining size ∈₂ of grains and of particles due to recrystallization/globularization processes. Proposed method ensures obtaining of homogeneous finegrained structure at grain size γ lesser than 5 mkm and size of α₂ particles lesser than 1 mkm. EFFECT: enhanced efficiency. 20 cl, 10 dwg, 1 tbl, 5 ex