Abstract

Titanium matrix composites (TMCs) reinforced with different TiB_w and La₂O_3p content were successfully processed by equal channel angular pressing (ECAP), and the role of reinforcements on the microstructure and mechanical properties were investigated. The results show that the addition of reinforcements accelerates continuous dynamic recrystallization (CDRX) and promotes the formation of new ultrafine grains (200 to 500 nm) in ECAPed TMCs. Micron-scale TiB_w accelerates recrystallization by particle-stimulated nucleation and the increasing effective strain. CDRX occurs more easily near TiB_w tips due to the load-bearing effect. By contrast, nano-scaled La₂O_3p retards the migration of grain boundaries through Zener drag effect and promotes the evolution of CDRX. The strength of ECAPed TMCs is improved significantly and reinforcements enhance the contribution of grain-refinement strengthening. The TMCs with 1.2 vol pct reinforcements exhibited the largest improvement in total strength, which is 5 times and 3 times of those with 0 vol pct and 2.4 vol pct, respectively. The elongations of both forged and ECAPed TMCs decrease with increasing reinforcement content owing to TiB whisker fracture and interface debonding and the diminishing strain hardening capacity.

中文翻译：

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了解多尺度增强对钛基复合材料严重塑性变形的作用

摘要

通过等通道角挤压（ECAP）成功地加工了不同TiB _w和La ₂ O _3p含量的钛基复合材料（TMCs），并研究了增强物对组织和力学性能的影响。结果表明，增强材料的添加加速了连续动态重结晶（CDRX），并促进了ECAPed TMC中新的超细晶粒（200至500 nm）的形成。微米级的TiB _w通过颗粒刺激的成核作用和增加的有效应变来加速重结晶。由于负载效应，在TiB _w尖端附近更容易发生CDRX 。相比之下，纳米级La ₂ O _3p通过齐纳阻力效应阻止了晶界的迁移，并促进了CDRX的演化。ECAPed TMC的强度得到显着提高，增强材料增强了晶粒细化增强的作用。具有1.2体积pct增强材料的TMC表现出最大的总强度提高，分别是0体积pct和2.4体积pct的5倍和3倍。由于TiB晶须断裂和界面脱粘以及应变硬化能力降低，锻造和ECAP的TMC的伸长率均随着增强含量的增加而降低。