金属Ti/Mg基非晶双连续相复合材料制备及其性能

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	金属Ti/Mg基非晶双连续相复合材料制备及其性能
	孙羽
学位类型	博士
导师	张海峰
	2010
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	非晶合金复合材料多孔钛双连续相剪切带
摘要	"Mg基非晶在室温下基本上没有塑性，极易发生脆性断裂，要开发Mg基非晶的实际应用必须要克服这一缺点。本文在研究Mg基非晶形成能力和力学性能的基础上，开发制备新型Mg基非晶复合材料，并对其变形和断裂行为进行深入的研究。本文在Mg(CuxAgy)Er伪三元共晶合金系中， x:y=6:4、2:1和7:3这三个成分面上寻找到了各个成分面的最佳非晶形成合金以及非晶形成尺寸随成分变化分布图，最佳非晶形成合金分别为Mg61Cu20.3Ag8.7Er10、Mg60.5Cu19.667Ag9.833Er10和Mg63Cu16.8Ag11.2Er9，其最大非晶形成尺寸分别为10mm、11mm和8mm。对MgCuAgEr非晶合金的压缩力学性能和合金成分之间的关系研究表明，MgCuAgEr非晶合金的压缩力学响应对杨氏模量参数比较敏感，在Mg(CuxAgy)Er伪三元共晶合金系中x:y= 7:3的合金成分面上出现了力学性能最优的非晶合金，为Mg63Cu16.8Ag11.2Er9。该非晶合金铸态直径为2mm的压缩试样断裂强度高达1.1GPa，该非晶合金还能表现出0.5%的压缩塑性。对Mg63Cu16.8Ag11.2Er9非晶合金的压缩稳定性采用Weibull方程进行表征，该非晶合金的Weibull常数为28。 MgCuAgEr非晶合金与钛金属在高温下的界面反应受体扩散控制，并且受温度的影响显著，在制备双连续相Mg基非晶复合材料时，合金熔体浸渗温度不能超过620°C、保温时间不能超过4分钟。采用610°C浸渗并保温2分钟的工艺条件，成功制备出多孔钛骨架增强Mg基非晶复合材料，此复合材料具有更为优异的压缩塑性，其压缩断裂应变为31%，断裂强度为1.75GPa。对两种不同的双连续相Mg基非晶复合材料，界面反应产物较多的复合材料具有较弱的塑性变形能力；复合材料的屈服强度和断裂强度受复合相两相力学性能的影响，在具有相同非晶基体的条件下，多孔钛骨架结合强度高的非晶合金具有更高的压缩强度。双连续相Mg基非晶复合材料压缩载荷变形由非晶相中剪切带的扩展所控制；通过调整多孔钛骨架的孔隙率和孔径大小，我们能对复合材料的微观结构进行设计。制备得到的各种微观结构的复合材料屈服强度随多孔钛孔隙度的增加而增加，断裂强度和断裂应变都随多孔钛孔隙度的减小而增加。通过改变多孔钛的孔径大小也能改变复合材料的性能，减小多孔钛骨架的孔径大小，复合材料的屈服强度、断裂强度和断裂应变都在一定程度上会有所增加。其原因是由于Mg基非晶的尺寸效应。在拉伸载荷下，双连续相Mg基非晶复合材料几乎没有表现出拉伸塑性，而且其屈服强度也远低于压缩载荷下屈服强度。三点弯曲试验表明，双连续相Mg基非晶复合材料拉应力作用下，裂纹优先从非晶基体中萌生。即使多孔钛骨架对张开型裂纹的扩展具有一定的限制作用，复合材料仍然表现出较低的抗裂纹扩展能力。"
其他摘要	"Mg-based bulk metallic glass has attractive properties of high specific strength and high elastic limits, which promote this new engineering material obtaining strong application prospect. However, Mg-based bulk metallic glass shows very little macroscopic plastic deformation due to the fast propagation of several dominating shear bands, and break into pieces catastrophically before yielding. Fabricating metallic glass into composite could be a method to solve this problem. In this thesis, we investigate the correlation of the glassy forming ability and the mechanical of MgCuAgEr alloy firstly, and then we develop a new Mg-based metallic glass composite with optimized fabrication procedure. After that we systemically study the deformation and fracture behavior of the composite. Systematic searching the MgCuAgEr alloy systemin 3D space, the best glass forming composition Mg60.5Cu19.667Ag9.833Er10 with critical diameter of 11mm is successfully detected. The Mg63Cu16.8Ag11.2Er9 BMG exhibits yielding and plastic deformation during compressive loading. The fracture strength and plastic strain of Mg63Cu16.8Ag11.2Er9 BMG is 1098MPa and 0.5%, respectively. Compare with other Mg-based BMGs with Y or Gd, the superior mechanical properties of the BMGs in this study are attributed to the introduction of Er element which has higher Young’s modulus. The reliability of compressive fracture strength of Mg63Cu16.8Ag11.2Er9 BMG is analyzed by Weibull statistics method, and its Weibull index has a value of 28. The interfacial reaction of the MgCuAgEr BMG melting alloy and titanium is controlled by the interfacial diffusion, and exhibits strong temperature dependence. While fabrication Mg-based metallic glass interpenetrating phase composite, the infiltrating temperature can not exceed 630°C, and the holding time for fully infiltrating can not exceed 4 minutes. By Fabricating Mg63Cu16.8Ag11.2Er9 alloy and porous titanium at 610°C and holding for 2 mins, we successfully prepare Mg-based metallic glass interpenetrating phase composite exhibiting excellent compressive mechanical behavior of a fracture strain of 31% and fracture stress of 1.75GPa. The interfacial structure has a significant effect for the plastic deformation of the composite, and the strength of the composite is depend on the properties of the porous titanium. The compressive deformation of the Mg-based metallic glass interpenetrating phase composite is dominated by the propagation of the shear band on the glassy phase. By adjusting the porosity and pore size of the porous titanium, the microstructure of the composite can be designed and optimized. By doing that, we conclude the empirical tendency the yield strength of the composite increases with the decreasing of porosity of porous titanium, and the facture strength and fracture strain exhibit the opposite tendency. The pore size of the porous titanium also affects the mechanical behavior of the composite, which the composites obtain larger yield strength, facture strength and strain with low pore size due to the “size effect” of Mg-based metallic glass. Under tensile stress, the Mg-based metallic glass interpenetrating phase composite exhibits very little plastic deformation at low stress. Three point bending test shows that cracks are initiated on the glassy phase. Although the porous titanium has the ability to arrest crack propagation on some extend, the composite still exhibits low crack tolerance under tensile stress."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64177
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	孙羽. 金属Ti/Mg基非晶双连续相复合材料制备及其性能[D]. 北京. 中国科学院金属研究所,2010.