摘要
The phase transformation and mechanical behavior of Ti-43Al-9V-0.2Y alloy under varied heat treatments were systematically investigated.The cooling phase sequence is identified as β→β+α→α→γ+α(α_(2))→β+γ+α(α_(2))→β(β_(0))+γ.Above 1240℃,slow cooling forms lamellar structures via α→γ+α(α_(2))→β+γ+α(α_(2)),while fast cooling follows α→γ+α→β(β_(0))+γ;below 1240℃,α→γ+α(α_(2))dominates.At 800℃ and 1.0×10^(−4)s^(−1),γphase in duplex microstructures restricts dislocation slip due to low stacking fault energy,promoting dynamic recrystallization.Mixed microstructure(γ/β_(0) lamellar and duplex microstructure)achieves a remarkable strength-ductility product of 4907 MPa%through synergistic effects:the duplex enhances plasticity,while the lamellar improves strength.In both microstructures,limited dislocation slip/climb in β_(0) phases creates dislocation density gradients at γ/β_(0) interfaces,inducing micro-void nucleation and microcracks in β_(0).γ phase impedes defect propagation,and micro-voids further suppress crack growth.The crack propagation in α_(2)/γ lamellar microstructure depends on stress direction:parallel stress hinders crack initiation and growth,while perpendicular stress promotes crack nucleation and expansion.
基金
supported by the National Natural Science Foundation of China(Nos.52201035 and FRF-TP-24-010A).
