The in situ nano Ta₄HfC₅ reinforced SiBCN-Ta₄HfC₅ composite ceramics were prepared by a combination of two-step mechanical alloying and reactive hot-pressing sintering. The microstructural evolution and mechanical properties of the resulting SiBCN-Ta₄HfC₅ were studied. After the first-step milling of 30 h, the raw materials of TaC and HfC underwent crushing, cold sintering, and short-range interdiffusion to finally obtain the high pure nano Ta4HfC5. A hybrid structure of amorphous SiBCN and nano Ta₄HfC₅ was obtained by adopting a second-step ball-milling. After reactive hot-pressing sintering, amorphous SiBCN has crystallized to 3C-SiC, 6H-SiC, and turbostratic BN(C) phases and Ta₄HfC₅ retained the form of the nanostructure. With the in situ generations of 2.5 wt% Ta₄HfC₅, Ta₄HfC₅ is preferentially distributed within the turbostratic BN(C); however, as Ta₄HfC₅ content further raised to 10 wt%, it mainly distributed in the grain-boundary of BN(C) and SiC. The introduction of Ta₄HfC₅ nanocrystals can effectively improve the flexural strength and fracture toughness of SiBCN ceramics, reaching to 344.1 MPa and 4.52 MPa·m^1/2, respectively. This work has solved the problems of uneven distribution of ultra-high temperature phases in the ceramic matrix, which is beneficial to the real applications of SiBCN ceramics.

在原位纳米的Ta ₄的HfC ₅增强SiBCN-TA ₄的HfC _5个通过两步机械合金化和反应性热压烧结的组合制备的复合陶瓷。研究了所得SiBCN-Ta ₄ HfC ₅的微观结构演变和力学性能。经过30个小时的第一步研磨，对TaC和HfC的原料进行粉碎，冷烧结和短程相互扩散，最终获得了高纯度的纳米Ta4HfC5。非晶态SiBCN与纳米Ta ₄ HfC _5的混合结构通过第二步球磨获得。反应性热压烧结后，非晶SiBCN结晶为3C-SiC，6H-SiC和涡轮层BN（C）相，Ta ₄ HfC ₅保留了纳米结构的形式。通过原位生成2.5 wt％的Ta ₄ HfC ₅，Ta ₄ HfC ₅优先分布在涡轮层BN（C）内。但是，随着Ta ₄ HfC _5的含量进一步增加至10wt％，它主要分布在BN（C）和SiC的晶界中。Ta ₄ HfC ₅的介绍纳米晶体可以有效提高SiBCN陶瓷的弯曲强度和断裂韧性，分别达到344.1 MPa和4.52 MPa·m ^1/2。这项工作解决了陶瓷基体中超高温相分布不均匀的问题，有利于SiBCN陶瓷的实际应用。