Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China.
Science. 2022 Nov 11;378(6620):659-663. doi: 10.1126/science.abq7739. Epub 2022 Nov 10.
Creep, the time-dependent deformation of materials stressed below the yield strength, is responsible for a great number of component failures at high temperatures. Because grain boundaries (GBs) in materials usually facilitate diffusional processes in creep, eliminating GBs is a primary approach to resisting high-temperature creep in metals, such as in single-crystal superalloy turbo blades. We report a different strategy to inhibiting creep by use of stable GB networks. Plastic deformation triggered structural relaxation of high-density GBs in nanograined single-phased nickel-cobalt-chromium alloys, forming networks of stable GBs interlocked with abundant twin boundaries. The stable GB networks effectively inhibit diffusional creep processes at high temperatures. We obtained an unprecedented creep resistance, with creep rates of 10 per second under gigapascal stress at 700°C (61% melting point), outperforming that of conventional superalloys.
蠕变是指在屈服强度以下的应力作用下材料的时变变形，它是高温下大量部件失效的原因。由于材料中的晶界（GB）通常有利于蠕变过程中的扩散，因此消除 GB 是抵抗金属高温蠕变的主要方法，例如在单晶高温合金涡轮叶片中。我们报告了一种通过使用稳定的晶界网络来抑制蠕变的不同策略。在纳米晶单相镍-钴-铬合金中，高密度晶界的塑性变形引发了结构弛豫，形成了与大量孪晶边界交错的稳定晶界网络。稳定的晶界网络有效地抑制了高温下的扩散蠕变过程。我们获得了前所未有的抗蠕变能力，在 700°C（约 61%熔点）下千兆帕斯卡应力下的蠕变速率约为 10 秒-1，优于传统的高温合金。
