【摘要】 利用混合元素烧结法制备含0、0.4、1.2和2.0wt.%Fe的Ti5553合金。研究Fe元素对绝热ω目变、α相析出长大以及时效硬化行为的影响规律。结果表明,2wt.%Fe元素的加入可提高β相的稳定性,抑制绝热ω相析出。随着Fe含量增加,α相析出孕育期变长,尺寸变小。α相沿晶析出倾向增强,尤其是在炉冷时,Ti5553-2Fe合金形成明显的魏氏组织。随后,利用Pandat软件并结合经典动力学理论分析Fe含量对Ti5553合金α相析出长大行为的影响机制。硬度曲线表明,不同Fe含量合金的硬度均随时效时间延长先增加,6h达到峰值后缓慢降低。Ti5553-2Fe合金具有最高的峰值硬度,这是Fe等合金元素点阵错配引起的固溶强化与细小α相析出引起的时效强化共同作用的结果。更多还原

【Abstract】 Ti5553-xFe(x=0.4, 1.2.,2.0, wt.%) alloys have been designed and fabricated through BE(blended element) sintering to investigate the effect of Fe-addition on athermal ω-phase transformation, a-phase evolution and age hardening behavior. The results show that the formation of athermal ω-phase is fully suppressed in water-quenched specimens when Fe-addition is up to 2 wt.%. The relevant timescales of a formation during initial stages of aging indicate that incubation time increases with Fe-addition. Further aging results in continuous nucleation and growth of a-phase but finer intragranular a lamellae exhibit in Ti5553-2 Fe alloy. In addition, the width and extent of grain boundary a-film increase slightly with incremental Fe-addition, especially in furnace cooling condition. Result of Vickers hardness manifests that Fe-addition leads to a strong hardening effect in both solution and aging treatment. The solid solution strengthening is quantitatively estimated by ab initio calculation based on the Labusch-Nabarro model.The evolution of a-precipitate is rationalized by Gibbs free energy. The prominent hardening effect of Ti5553-2 Fe alloy is attributed to both large lattice misfit of β-matrix and fine a-precipitate distribution.更多还原