时效温度对Ti-5Al-4Zr-10Mo-3Cr钛合金微观组织及力学性能的影响

Precipitation behavior and mechanical properties of secondary α phase (α_s) in the Ti-5Al-4Zr-10Mo-3Cr alloy after solution treatment in β phase region (at 880℃) and aging at different temperatures (540-620℃) were studied. The results show that with the aging temperature increasing from 540℃ to 620℃, the thickness of precipitated α_s increases from 0.030 μm to 0.142 μm, the yield strength decreases from 1353 MPa to 1074 MPa, and the elongation after fracture increases from 2.5% to 11.4%. This indicates that the micro-scaled α_s precipitated by aging can regulate the mechanical properties of the alloy. In addition, with the increase of aging temperature, the tensile fracture of the alloy changes from intergranular brittle fracture to dimple transgranular ductile fracture. The thickness of the α precipitation in the Ti-5Al-4Zr-10Mo-3Cr alloy is greater than 0.1 μm, which brings about the elongation after fracture larger than 6%. When the aging temperature is 600℃, the hardness, tensile strength and elongation after fracture are 387 HV10, 1182 MPa and 8.5% respectively, possessing good combination of strength and ductility.