SiC/Zr基非晶合金双连续相复合材料的制备及其力学行为

IMR OpenIR

	SiC/Zr基非晶合金双连续相复合材料的制备及其力学行为
	陈永力
学位类型	博士
导师	张海峰 ; 王爱民
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料学
关键词	非晶合金复合材料双连续相 Sic骨架力学性能 Metallic Glasses Porous Sic Preforms Composite Materials Interpenetrating Phase Mechanical Properties
摘要	"块状非晶合金由于其优异的力学性能获得了广泛的关注，但是在室温和高应力条件下表现为高度局域化的非均匀塑性流变，其室温宏观塑性几乎为零，限制了非晶合金作为结构材料的应用。目前通过采用内生或外加的方法引入第二相制成非晶合金基复合材料能够有效地改善了其室温塑性变形能力，从而扩展其应用领域。本论文工作采用三维连通的多孔SiC预制体作为第二相，通过压力浸渗铸造法制备出高比强度的SiC/Zr基非晶合金双连续相复合材料，并系统地研究了该复合材料的力学性能与变形断裂行为及组织性能相关规律。本论文首先通过座滴法研究Zr41.2Ti13.8Ni10.0Cu12.5Be22.5合金熔体在多孔SiC基片上的润湿性、界面反应以及浸渗行为。结果表明：温度在1053 K以上时，合金熔体与SiC基片具有良好的润湿性；在1103 K以上时，合金熔体在多孔SiC基片上能够发生自发浸渗，但仅依靠自发浸渗难以完全填充到多孔SiC的开放孔隙之中；同时，合金熔体与SiC基片在界面处能够发生元素间的相互溶解扩散并形成约5 μm的扩散反应层。在此基础上，我们确定了合理的复合材料制备工艺。选取两种网络结构的多孔SiC预制体，利用压力浸渗铸造法在1103 K保温3~5 min成功地制备出系列体积分数的SiC/ZrTiNiCuBe非晶合金双连续相复合材料。微观结构研究表明该复合材料的组成相均呈三维连通的网络结构，并且两相分布均匀，界面结合良好，在界面处无宏观裂纹、孔洞等缺陷。界面分析表明在SiC相和非晶合金相之间存在1~2 μm的相互扩散层，同时细小的颗粒状反应产物（ZrC与TiC的混合物）组成了宽度约为300 nm的界面反应层。进一步研究了系列双连续相复合材料的室温准静态压缩力学行为，分析了SiC体积分数对上述材料的力学性能及变形断裂行为的影响。结果表明：SiC泡沫/ ZrTiNiCuBe非晶合金双连续相复合材料在整个室温准静态压缩过程中表现为弹性变形，其宏观断裂方式为剪切断裂，剪切断裂角约为40°；断口上的非晶合金相主要呈现细、浅的“河流状”脉纹花样，而SiC相则呈现出大量穿晶断裂后的解理台阶。结合断口分析与压缩断裂前后的侧表面形貌观察，发现微观尺度上的不规则粗糙界面是该复合材料在受力变形过程中的薄弱环节。随着SiC体积分数从51%增加到82%，SiC骨架/ZrTiNiCuBe非晶合金双连续相复合材料的室温准静态压缩行为呈现出从弹性-塑性变形到线弹性变形的转变，同时其宏观断裂方式也由剪切断裂转变为轴向劈裂，我们根据Mohr-Coulomb准则分析了该复合材料剪切断裂行为与轴向劈裂行为的竞争机制。断口分析表明，51% Vf复合材料的断口形貌主要由非晶合金相的粘滞流变特征和SiC相的解理断裂特征组成，而82% Vf复合材料则以SiC相的解理断裂特征和两相的界面分离特征为主。我们采用Selsing模型分析了上述两种体积分数复合材料内部热残余应力场的分布，讨论了热残余应力场对于非晶合金相中剪切带以及SiC相中裂纹扩展路径的影响。接着，采用分离式霍普金森压杆装置（SHPB）对51% Vf复合材料进行动态力学性能测试。通过波形整形技术，在SHPB实验过程中实现了~500 s-1到~1700 s-1的一系列常应变率加载，研究了两种长径比的51% Vf复合材料试样在动态载荷作用下的力学性能及变形断裂行为。结果表明，Φ5 mm×5 mm的试样表现为负的应变率敏感性，呈现出典型的剪切断裂特征；而Φ5 mm×2.5 mm的试样则表现为正的应变率敏感性，在断裂后形成了若干的小体积碎块，但是相同尺寸试样的峰值应力均随着应变速率的升高呈现出线性增加的趋势。断口分析表明，在动态加载下，SiC相的破碎情况较准静态时更加严重，形成了更多的细小碎块；而非晶合金相的粘滞流变现象也更加明显，表现出大范围的局部熔融后的流动现象。最后，通过对51% Vf SiC骨架/ ZrTiNiCuBe非晶合金双连续相复合材料在不同温度下（173 K~573 K）的压缩力学性能测试，发现该复合材料在低于室温的试验温度下，其压缩变形行为主要受到非晶合金相中原子活动能力的影响，复合材料的强度随着环境温度的降低而升高；当压缩试验温度高于室温时，在复合材料变形的同时伴随着其中非晶合金相的结构弛豫过程，复合材料的压缩变形行为主要受到非晶合金相结构弛豫的影响，其压缩强度随着试验温度的升高而增大。通过对SiC/ZrTiNiCuBe非晶合金双连续相复合材料制备工艺、组织性能和变形行为的规律性研究，为该种复合材料的制备提供技术指导，并为该复合材料的应用提供实验基础及理论支持，以期能够扩大非晶合金复合材料的应用领域。"
其他摘要	Bulk metallic glasses (BMGs) have promising mechanical properties. However, monolithic BMGs always fail catastrophically with limited macroscopic plasticity because they exhibit highly-localized inhomogeneous plastic flow under high stress level at room temperature, which limits their application as structure materials. The motivation to improve the poor ductility of BMGs leads to the development of a variety of BMG matrix composites reinforced with in situ or ex situ second phases. The main purpose of this paper is to fabricate SiC/ Zr-based metallic glass interpenetrating phase composites (IPCs) with high specific strength, which are expected to be applied as composite armor. Firstly, the wettability, interfacial reaction and infiltration behavior of molten Zr41.2Ti13.8Ni10.0Cu12.5Be22.5 alloy on porous SiC substrate were investigated by sessile drop method under high vacuum. It is found that the ZrTiNiCuBe melt has a good wettability with the SiC substrate above 1053 K and the melt can infiltrate spontaneously into the porous SiC substrate above 1103 K. However, the melt could not completely fill into the open cells of the porous SiC substrate by spontaneous infiltration solely. Thus, the pressure-infiltration casting method was chosen to fabricate a series of volume fraction (Vf ) of SiC/ ZrTiNiCuBe MG IPCs reinforced with two different kinds of porous SiC preform. It is found that the voids of the porous SiC preform are fully filled with the melt which was quenched into an amorphous state during subsequent solidification and both the glassy phase and SiC phase exhibit a three-dimensional interconnected structure. Microstructure investigation reveals that an 1~2 μm width diffusion reaction layer, which consists of 300 nm width ZrC and TiC mixture, appears at the interface. Secondly, deformation and fracture behaviors of SiC foam/ ZrTiNiCuBe MG IPC and SiC skeleton/ ZrTiNiCuBe MG IPC were investigated and discussed by changing the SiC Vf under quasi-static compression at room temperature. The SiC foam/ ZrTiNiCuBe MG IPCs show an elastic deformation behavior before shear fracture at an angle of 40°, and their fracture morphologies mainly consist of river-like vein patterns from the MG phase and cleavage steps from the SiC phase. Based on fractography analysis and SEM observation of pre-polished side surfaces of the IPCs before and after deformation, it is proposed that microscopic irregular interface is the vulnerable region under compressive deformation. With the increase of the SiC volume fraction from 51% to 82%, the quasi-static compressive behavior of the SiC skeleton/ ZrTiNiCuBe MG IPCs changes from elastic-plastic deformation to elastic deformation, and the fracture behavior also changes from a shear mode to an axial splitting one. The competition mechanism between shear fracture and axial splitting fracture was discussed by the Mohr-Coulomb criterion. The dominant fracture morphologies of the 51% Vf IPC are viscous flow features from the MG phase and typical cleavage features from the SiC phase, while the 82% Vf IPC mainly shows river patterns and cleavage steps on the SiC phase together with extensively interface debonding features. The distribution of thermal residual stress for the two Vf SiC skeleton/ ZrTiNiCuBe MG IPCs was analyzed by Selsing mode, and the influence of thermal residual stress on the propagation path of the shear bands in the MG phase and the cracks in the SiC phase was also discussed. Thirdly, the split Hopkinson pressure bar (SHPB) was conducted to study the dynamic mechanical and fracture behavior of the 51% Vf SiC skeleton/ ZrTiNiCuBe MG IPC. For Φ5 mm×2.5 mm and Φ5 mm×5 mm samples, a series of constant-rate loading from ~500 s-1 to ~1700 s-1 was achieved by pulse shaping method in the SHPB tests. The Φ5 mm×5 mm samples always show negative strain rate sensitivity and fail by shear fracture, while the Φ5 mm×2.5 mm samples show positive sensitivity and fracture into numerous small fragments. However, the peak stress from the same size samples increases linearly with the strain rate. Compared to the quasi-static compression, the SiC phase fractured more seriously into extensive tiny fragments and the MG phase showed more obvious viscous flow feature caused by local melting under dynamic compression. Finally, the influence of ambient temperature on compressive behavior of the 51% Vf SiC skeleton/ ZrTiNiCuBe MG IPC was investigated from 173 K to 573 K. At temperatures below room temperature, it is found that the deformation behavior of the 51% Vf IPC is dominated by atom motion ability in the glassy phase and the strength of the 51% Vf IPC increases with the decrease in testing temperature. When the testing temperature is above room temperature, structure relaxation occurrs in the glassy phase during the deformation process of the 51% Vf IPC. As a result, the deformation behavior of the 51% Vf IPC is mainly affected by the structure relaxation in the glassy phase and the strength of the 51% Vf IPC increases with the testing temperature."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64415
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	陈永力. SiC/Zr基非晶合金双连续相复合材料的制备及其力学行为[D]. 北京. 中国科学院金属研究所,2012.