【作者】 胡少虬；

【导师】 曾苏民； 金展鹏；

【作者基本信息】 中南大学 ， 材料加工工程， 2007， 博士

【摘要】 以微观组织设计为核心,采用相图—微观组织设计—工艺—性能的研究思路,进行了相图计算、相变分析及相的鉴定,为工艺设计提供了科学可靠的理论和实验依据,研制出新型大尺寸喷射沉积超高强度高弹性模量高塑性铝合金（Al—10.0Zn—3Mg—1.6Cu—0.8Ni—0.8Zr,Fe<0.1wt%,Si<0.05wt%）。提出了优晶理论:晶粒尺寸最优（本合金是7μm）、析出相最优、固溶程度最优和这三者配合最优。以相图为基础,通过长时间多级固溶,将组织统一为单一的细小均匀的充分再结晶组织,实现最佳固溶序列和时效脱溶序列的合理匹配,实现强度、塑性和弹性模量等综合性能同步提高。为该合金设计了全套工艺,特别是开发出独特的四级固溶工艺和三级时效工艺,对φ150×260mm试样实现平均抗拉强度σ_b=770MPa,平均屈服强度σ_0.2=730MPa,平均延伸率δ=9%,平均弹性模量E=75.5GPa。提出了理想固溶时效工艺设计理论及经验公式。合金性能整体水平达到了美国2002年最新开发的7085合金的研究水平（平均抗拉强度σ_b=770MPa,平均延伸率δ=11%,平均弹性模量E=72GPa）。自动化控制的关键在于确认设备之间的核心关系式及明确判别标准,可以实现喷射沉积材料的组织稳定性和最优化,大幅度提高喷射沉积材料的质量。通过研究喷射沉积工艺流程自动化控制的五个核心关系式,为喷射沉积设备全面自动化改造奠定了核心技术。系统和全面地深入研究了淬火热应力、塑性变形、残余应力、淬火界面、试样形貌的演变规律,建立了一系列拓扑模型,发现了淬火角端效应、淬火动态薄膜效应、微观和宏观淬火塑性变形机制、塑性变形驱动力机理、应力变化规律、残余应力形成机制及分布规律、淬火塑性变形区形状变化规律和厚度对淬火残余应力影响规律等等,创立了全新的淬火残余应力研究体系,全面突破了70年代日本学者米谷茂建立的残余应力两层结构的经典模型。更多还原

【Abstract】 With microstructure design as the core,phase diagram - microstructure design - processing technology - properties is supposed as the main route for materials design.And the phase diagrams,corresponding phase transformation and phase of the Al-Zn-Mg-Cu alloy are calculated and characterized.All of these help the design of high strength,high modulus and high ductility aluminum alloys,and as an example the lager section jet spray aluminum alloy (Al-10.0Zn -3Mg-1.6Cu-0.8Ni-0.8Zr,Fe＜0.1 wt%,Si＜0.05wt%)is designed in the present paper.The optimum grain and particle size theory is proposed for design of high performance aluminum alloys.The matching of grain of matrix, precipitate and the solution extent is the core of high performance aluminum alloy.Based on the phase diagram,a homogeneous and fully recrystallized fine grain and the optimum matching of solution and precipitation sequence are obtained by long time three-stage solution treatment.The strength, ductility and modulus of the investigated alloy are improved together.An empirical equation for solution and aging treatment of the investigate alloy is proposed.A complete processing technology,especially the four-stage solution treatment and three-stage aging treatment,for the investigated alloy is developed in the present paper.The average ultimate strength of the investigated alloy by this series of processing technology is 770MPa;average yield strength is 730MPa,average elongation rate is 9%and average modulus is 75.5Gpa inφ150×260mm workpice.The mechanical properties are better than those of the alloy 7085,which is developed by US in 2002.The equations for description of the relationship between equipments play a critical role for computer control of jet spray equipments,which can improve the quality of ingots substantially.Five critical equations are proposed in the present paper,which made the foundation for computer control of jet spray equipments.A series of topological models are proposed for analysis of residual stress of aluminum workpieces,which completely discard the classical two-layer structure model by Japanese researchers in the 70s for investigation of residual stress.The thermal stress,plastic deformation and residual stress of quenched workpieces are systemically and thoroughly investigated with this series of topological model.The comer effect,quenching dynamic film effect, micro- and macro-plastic deformation mechanism due to quenching,driving force for plastic deformation,stress evolution pattem,the formation and distribution mechanism of residual stress and so on are revealed with the topological model.A completely novel system for investigation of residual stress is established.更多还原