It is well known that diamond does not deform plastically at room temperature and usually fails in catastrophic brittle fracture. Here, we demonstrate room-temperature dislocation plasticity in submicrometer-sized diamond pillars by in situ mechanical testing under the transmission electron microscope. We document in unprecedented details of spatiotemporal features of the dislocations introduced by the confinement-free compression, including dislocation generation and propagation. Atom-resolved observations with tomographic reconstructions show unequivocally that mixed-type dislocations with Burgers vectors of 1/2<110> are activated in the non-close-packed {001} planes of diamond under uniaxial compression of <111> and <110> directions, respectively, while being activated in the {111} planes under the <100> directional loading, indicating orientation-dependent dislocation plasticity. These results provide new insights into the mechanical behavior of diamond and stimulate reconsideration of the basic deformation mechanism in diamond as well as in other brittle covalent crystals at low temperatures.

众所周知，金刚石在室温下不会塑性变形，并且通常不会在灾难性的脆性断裂中失效。在这里，我们通过原位演示了室温下亚微米级金刚石柱的位错可塑性透射电子显微镜下的机械测试。我们以无限制的压缩引入了位错的时空特征的空前细节，包括位错的产生和传播。层析成像重建的原子分辨观察结果清楚地表明，在<111>和<110>的单轴压缩下，具有Burgers向量1/2 <110>的混合型位错在金刚石的非密堆积{001}平面中被激活。方向分别在<100>方向载荷下在{111}平面中被激活时，指示与方向有关的位错可塑性。