A heat treatment method for regulating near lamellar structure of additive manufacturing TiAl alloy

Abstract

This invention provides a heat treatment method for controlling the near-lamellar microstructure of additively manufactured TiAl alloys, relating to the technical field of additive manufacturing of TiAl alloys. The method includes the following steps: S1, preparation of Si-containing Nb-TiAl alloy: using electron beam powder bed melting (EB-PBF) technology to prepare an Nb-TiAl alloy containing 1.0-1.5% Si; S2, performing a two-step heat treatment on the Nb-TiAl alloy: S201, heating the Nb-TiAl alloy from S1 to the α single-phase region T... α +10℃~T α Within a temperature range of +20℃, the alloy is held at this temperature and then furnace cooled. In step S202, the high-Nb-TiAl alloy treated in step S201 is cooled in the furnace to the near-lamellar structure formation temperature, held at this temperature, and then air-cooled to room temperature, thus obtaining an additively manufactured TiAl alloy product with a near-lamellar structure. This invention controls the phase transformation path through a two-step heat treatment process and utilizes the pinning effect of the Ti5Si3 precipitate to inhibit grain growth and lamellar coarsening, achieving a synergistic improvement in the strength and plasticity of the TiAl alloy, making it suitable for manufacturing high-temperature structural components for aero-engines.

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