ABSTRACT The mechanical behaviour of a polycrystalline silicon carbide across length scales was studied using Vickers indentation, focusing on the hardness, fracture toughness and failure mechanism of the material. For macroscopic and microscopic indentations, the hardness decreased with an increase in load, which was associated with the well-known indentation size effect as well as the internal flaws. For nanoindentation, severe plastic deformation was discovered beneath the imprints on the basal plane (0001) which is the most favourable crystallographic plane for dislocation movement. Alternative sources of plastic deformation, including deformation twinning and stacking faults, were found for nanoindentations with an increased load. Also, cracking was observed for indents made at 100 mN and above, which was used to study the fracture toughness.

中文翻译：

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6H多晶碳化硅变形断裂的多尺度压痕研究

摘要 使用维氏压痕研究了多晶碳化硅在长度尺度上的机械行为，重点研究了材料的硬度、断裂韧性和失效机制。对于宏观和微观压痕，硬度随着载荷的增加而降低，这与众所周知的压痕尺寸效应以及内部缺陷有关。对于纳米压痕，在基面（0001）上的印记下方发现了严重的塑性变形，这是位错运动最有利的晶面。对于负载增加的纳米压痕，发现了塑性变形的替代来源，包括变形孪生和堆垛层错。此外，在 100 mN 及以上制造的压痕中观察到开裂，用于研究断裂韧性。