National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science and Engineering, P. O. Box 434. and Harbin Institute of Technology, Harbin 150001, China.
Nanoscale. 2018 Jun 21;10(24):11365-11374. doi: 10.1039/c8nr01659c.
Intermetallic alloys with high melting point can mostly serve as promising high-temperature structural materials, but their intrinsic brittleness limits their further application. Herein, we developed a strategy to realize high strength and high plasticity simultaneously in Cr-rich γ-TiAl-based intermetallic alloys via introducing high-density deformation nanotwins. Non-equilibrium continuous casting followed by annealing in the (α + γ) phase region generated numerous Shockley partial dislocations and stacking faults as well as a number of α2 nanoparticles in the γ-TiAl phase. The substantial Shockley partial dislocations and stacking faults acting as effective heterogeneous nucleation sites favored the generation of high-density nanotwins in the as-annealed alloys during deformation, especially within the γ lamellae. This strategy can also be applied to other brittle alloys with a favorable twinning deformation mechanism and paves the way for the development of high-strength and high-ductility materials.
具有高熔点的金属间化合物大多可用作有前途的高温结构材料，但它们的固有脆性限制了它们的进一步应用。在此，我们通过引入高密度变形孪晶，开发了一种在富 Cr γ-TiAl 基金属间化合物中同时实现高强度和高塑性的策略。非平衡连铸后在（α+γ）相区退火，在 γ-TiAl 相中产生了大量的 Shockley 不全位错和层错以及一些 α2 纳米粒子。大量的 Shockley 不全位错和层错作为有效的异质形核点，有利于在变形过程中在退火后的合金中产生高密度的孪晶，尤其是在 γ 层内。这种策略也可以应用于具有有利孪生变形机制的其他脆性合金，为开发高强度和高延展性材料铺平了道路。
