高能离子梯度多剂量辐照4H-SiC的微结构及硬度变化研究

为探讨高温高能离子辐照碳化硅后的结构和力学性能随剂量的变化，应用拉曼光谱和纳米压痕技术研究了122 MeV的²⁰Ne⁴⁺离子梯度多剂量辐照后的4H-SiC。研究表明，SiC的相对拉曼强度随剂量的增大呈指数规律下降，并出现了代表无序化Si-C键和同核Si-Si键的散射峰。基于DI/DS模型的初步拟合表明，在低剂量范围内扩展缺陷簇是引起SiC无序化的主要因素，高剂量范围内的无序化则是由离子直接碰撞过程的非晶化和扩展缺陷簇共同引起。辐照后的SiC硬度取决于位错钉扎和共价键断裂的共同作用，在0～4.00 dpa之间硬度随剂量增大而增大，在4.00～8.05 dpa之间硬度随剂量增大而减小，剂量在8.05 dpa时，硬度相比于未辐照区域略高，此时共价键断裂和位错钉扎达到平衡。

Study on Microstructure and Hardness Changes of 4H-SiC Irradiated by High Energy Ion Gradient with Multiple Doses

In order to investigate the changes of structure and mechanical properties of silicon carbide irradiated by high energy ions, the 4H-SiC after 122 MeV 20Ne4+ ion gradient multi-dose irradiation was investigated by Raman spectrum and nano indentation technology. The Relative Raman Intensity of the sample decreases exponentially with the increase of dose, and there are scattering peaks representing disordered Si-C bond and homonuclear Si-Si bond. Preliminary fitting based on the DI/DS model shows that the expansion of defect clusters in the low dose range is the main factor causing the disorder, while the disorder in the high dose range is caused by amorphization in the process of direct ion collision and extended defect clusters. The hardness of irradiated silicon carbide is the joint action between dislocation pinning and covalent bond breaking. Between 0~4.00 dpa, the hardness increases with the increase of dose, and between 4.00~8.05 dpa, the hardness decreases with the increase of dose. At 8.05 dpa, the hardness is slightly higher than that unirradiated area. At the same time, the covalent bond breaking and dislocation pinning reach equilibrium.