Microstructural characterization of boron-rich boron carbide
Microstructural characterization of boron-rich boron carbide
复制标题
DOI：
10.1016/j.actamat.2017.06.063
复制
发表时间：
2017-09
期刊：
影响因子：
9.4
通讯作者：
K. Xie;V. Domnich;L. Farbaniec;Bin Chen;K. Kuwelkar;Luoning Ma;J. McCauley;R. Haber;K. Ramesh;Mingwei Chen;K. Hemker
中科院分区：
文献类型：
--
作者：
K. Xie;V. Domnich;L. Farbaniec;Bin Chen;K. Kuwelkar;Luoning Ma;J. McCauley;R. Haber;K. Ramesh;Mingwei Chen;K. Hemker
碳化硼具有广泛的溶解度，但化学计量对其微观结构和机械响应的影响还没有很好的理解。在这项研究中，详细的显微组织特征进行了三个热压富硼碳化硼样品。来自XRD的晶格参数测量确定组成为B4.2C、B5.6C和B7.6C。通过拉曼光谱，特别是对于更多的B-丰富的样品，观察到局部取代的障碍。电子能量损失谱的观察表明，过量的硼优先取代碳原子的B11 C二十面体，之后，额外的硼修改CBC链。硼含量对碳化硼的致密化和微观结构有显著影响。在更富B的样品（B5.6C和B7.6C）中观察到改进的致密化，并且存在从很少或没有晶内平面缺陷（B4.2C）到大量堆垛层错（B5.6C）再到大量孪晶（B7.6C）的过渡。纳米压痕实验表明，B4.2C的最高值在统计学上大于B5.6C或B7.6C，这表明硼取代降低了碳化硼的硬度。
Boron carbide has a wide range of solubility, but the effects of stoichiometry on its microstructure and mechanical response are not well understood. In this study, detailed microstructural characterization was carried out on three hot-pressed B-rich boron carbide samples. Lattice parameter measurements from XRD identified the compositions to be B4.2C, B5.6C and B7.6C. Local substitutional disorder was observed by Raman spectroscopy, particularly for more B-rich samples. Electron energy loss spectroscopy observations suggest that excess boron preferentially substitutes for carbon atoms in the B11C icosahedra; after which additional boron modifies the CBC chains. Moreover, the boron content has salient effects on boron carbide densification and microstructure. Improved densification was observed in the more B-rich samples (B5.6C and B7.6C), and there is a transition from few or no intragranular planar defects (B4.2C), to numerous stacking faults (B5.6C), to copious twins (B7.6C). Nanoindentation experiments revealed that the highest value for B4.2C is statistically larger than that for B5.6C or B7.6C, suggesting that the hardness of boron carbide is reduced by boron substitution.