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High-pressure sintering of bulk MoSi2: Microstructural, physical properties and mechanical behavior
Materials Science and Engineering: A ( IF 6.4 ) Pub Date : 2017-11-08 , DOI: 10.1016/j.msea.2017.11.016
Hao Liang , Fang Peng , Haihua Chen , Lijie Tan , Qiang Zhang , Cong Fan , Shixue Guan , Xiaolin Ni , Akun Liang , Xiaozhi Yan , Qiwei Hu

In this study, using MoSi2 powder as starting material, the bulk MoSi2 samples were sintered at 1000–1600 °C under 5.5 GPa in a DS6 × 14MN cubic press. Furthermore, their sintering behavior and mechanical properties were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM) and indentation tests. XRD results elucidate that MoSi2 can still maintain its body-centered-tetragonal structure after the high pressure and high temperature (HPHT) sintering. SEM images imply the combination between grain growths and re-crystallization. Strong covalent bonding between the grains is crucial for improving the mechanical properties of samples. But re-crystallization results in a large number of pores between grains in the sintered body, so that the density and hardness was reduced. Indentation tests indicate that sintered MoSi2 have hardness values of 13.6–15.0 GPa, which increase with increasing temperature and is harder than polycrystalline and single crystal MoSi2. The results demonstrate that the sintered MoSi2 at 5.5 GPa/1300 °C possesses outstanding mechanical properties, including a high relative density (6.23g/cm3), Vickers hardness (15.0 GPa) and fracture toughness (10.7 MPa m1/2) at applied load of 29.4 N. In addition, the oxidation resistance of the prepared samples is measured using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The results show that the oxidation resistance has been significantly improved from this work compared with polycrystalline MoSi2.



中文翻译:

块状MoSi 2的高压烧结:显微组织,物理性质和机械性能

在这项研究中,以MoSi 2粉末为原料,在DS6×14MN立方压力机中,在5.5 GPa下于1000–1600°C烧结块状MoSi 2样品。此外,通过X射线衍射(XRD),扫描电子显微镜(SEM)和压痕测试研究了它们的烧结行为和机械性能。XRD结果阐明了MoSi 2高压高温烧结后仍能保持其体心四角形结构。SEM图像暗示晶粒长大和再结晶之间的结合。晶粒之间的强共价键对改善样品的机械性能至关重要。但是再结晶导致在烧结体中的晶粒之间有大量的孔,从而降低了密度和硬度。压痕测试表明,烧结的MoSi 2的硬度值为13.6–15.0 GPa,随温度的升高而增加,并且比多晶和单晶MoSi 2硬度更高。结果表明,烧结后的MoSi 2 在5.5 GPa / 1300°C的温度下具有出色的机械性能,包括较高的相对密度(6.23G/厘米3),29.4 N的外加载荷下的维氏硬度(15.0 GPa)和断裂韧性(10.7 MPa m 1/2)。此外,使用热重分析(TGA)和差示扫描量热法(DSC)测量制备的样品的抗氧化性) 分析。结果表明,与多晶MoSi 2相比,这项工作显着提高了抗氧化性。

更新日期:2017-11-08
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