Effect of temperature on microstructure and mechanical properties of ECAPed (TiB + La 2 O 3 )/Ti-6Al-4V composites
Effect of temperature on microstructure and mechanical properties of ECAPed (TiB + La 2 O 3 )/Ti-6Al-4V composites
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温度对ECAPed (TiB La 2 O 3 )/Ti-6Al-4V复合材料显微组织和力学性能的影响
DOI：
10.1016/j.matchar.2018.10.004
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发表时间：
2018
影响因子：
4.7
通讯作者：
Weijie Lu
中科院分区：
文献类型：
--
作者：
Juan Xiang;Yuanfei Han;Jianwen Le;Guangfa Huang;Lv Xiao;Jiayu Liu;Weijie Lu
在600 °C ~ 900 °C温度范围内，成功地进行了TiB短纤维和La 2 O3颗粒增强钛基复合材料的等通道转角挤压（ECAP）。研究了ECAP温度对TMCs组织和力学性能的影响。结果表明，在较低的ECAP温度下，位错缠结在基体中形成胞状结构。相反，在较高的ECAP温度下发生连续动态再结晶，并促进大量新的超细晶的形成。随着ECAP温度的升高，TiB短纤维的平均长径比减小，导致界面脱粘。800 °C ECAP处理后的复合材料拉伸强度达到1128 MPa，比原始复合材料提高了18%。界面脱粘导致低长径比的TiB短纤维无法承受载荷，而超细晶粒的形成提高了TMCs的强度。这两个因素的耦合导致ECAP温度对拉伸强度的影响很小。然而，ECAP处理后的钛金属复合材料的延伸率普遍下降，这是由于应变硬化能力的损失。由于界面脱粘，TiB短纤维尖端附近易发生应力集中，导致裂纹扩展。这导致了早期断裂和低塑性。
TiB short fibers and La2O3particles reinforced titanium matrix composites (TMCs) were successfully equal-channel angular pressed (ECAPed) at 600 °C–900 °C. The effect of ECAP temperature on the microstructure and mechanical properties of the TMCs was investigated. The results indicated that dislocation tangling formed cell structures in matrix at lower ECAP temperature. In contrast, continuous dynamic recrystallization occurred at higher ECAP temperature, and promoted the formation of numerous new ultrafine grains. The average aspect ratio of TiB short fibers decreased with increasing ECAP temperature, which induced interfacial debonding. The tensile strength of TMCs ECAPed at 800 °C was up to 1128 MPa, which was 18% higher than the as-received composites. Interfacial debonding led TiB short fibers in low aspect ratios disabled to bear load, while the formation of ultrafine grains increased the strength of TMCs. The coupling of these two factors resulted in little effect of ECAP temperature on the tensile strength. However, the elongation of ECAPed TMCs generally decreased due to the loss of strain hardening capacity. Stress concentration tended to occur around the tips of TiB short fibers due to the interfacial debonding and cause crack propagation. It led to the premature fracture and low ductility.