材料期刊网

包套锻造Ti-45Al-5Nb-0.3Y合金由大量细小的动态再结晶等轴γ晶粒 (晶粒尺寸可达1-2 um) 、弯曲或破碎的层片和少量的残余平直层片组成, 变形组织含有大量位错及少量变形孪晶. 锻态试样抗拉强度 (σb)、延伸 率 (δ) 分别达到\linebreak 708.1 MPa 和0.95%. 再通过不同的热处理分别得到晶粒 细小的双态组织、近层片组织和全层片组织. 经1320 ℃/30 min炉冷后得到双态 组织, 层片晶粒尺寸 (d l) 约为20 um, 层片体积分数 (ψ l}$) 约为60%, 具有 最高的, 约为1.9%, σ b约为658.9 MPa, 为穿晶和沿晶混合断裂; 经 1340 ℃/30 min炉冷后得到近层片组织, d　l约为60 um, ψl约 为95%,σ b 约为 690.2 MPa, δ约为1.75%, 主要为穿晶 (层片) 断 裂; 经1370 ℃/15 min炉冷后得到细小全层片组织 (d　l约为40 um), 具有最 高的σ b, 约为715.1 MPa,δ约 为1.51%, 为穿晶断裂.

Thermo-mechanical treatments, through combined action of hot forging and heat treatment, were performed on a Ti-45Al-5Nb-0.3Y alloy to investigate their effect on the microstructure and mechanical properties of the alloy. As-forged Ti-45Al-5Nb-0.3Y alloy is comprised of a large number of dynamic recrystallization (DRX) γ grains, curved and broken lamellae, and a small amount of remnant lamellae. The DRX γ grain size reaches 1~2μm. The deformed regions contained lots of dislocations and a little deformation twinning. As-forged Ti-45Al-5Nb-0.3Y alloy presents better tensile properties in comparison to as-cast material at room temperature. The ultimate tensile strength of as-forged alloy is about 708.1MPa and the elongation is about 0.95%. The fine duplex (DP), near lamellar (NL) and fully lamellar (FL) microstructures are obtained by further heat treatment. These microstructures have better room temperature ductility. The DP microstructure with lamellar colony size of about 20µm and lamellar volume fraction of about 60% is obtained by 1320℃/30min/FC. The microstructure has the highest ductility of about 1.9% and ultimate tensile strength of about 658.9MPa, and shows the transgranular and intergranular cracks. The NL microstructure with lamellar colony size of about 60µm and lamellar volume fraction of about 95% is obtained by 1340℃/30min/FC. The microstructure has the ductility of about 1.75% and ultimate tensile strength of about 690.2MPa, and mainly shows the transgranular cracks. The FL microstructure with lamellar colony size of about 40µm is obtained by 1370℃/15min/FC. The microstructure has the ductility of about 1.5% and highest ultimate tensile strength of about 715.1MPa, and shows the transgranular cracks.