流变铸造内生块体非晶复合材料微观组织结构调控与高塑性

It is a effective method to modify the room temperature brittleness of the amorphous materials by making a crystal phase formation in the bulk amorphous composite materials. The rheological viscoplasticity of bulk amorphous composite in liquid-solid two-phase region near net shape is the new way to solve the bulk amorphous material forming. The application for the project to the Ti-Zr-(Ni)-Cu-Be-(V, Nb, Mo) system as the research object to build multi-component polycrystalline solidification - plastic deformation phase-field model of the whole process; Research the design of amorphous composite component, the law of organizational structure formation and the principle of controlling under the rheocasting conditions, devise and performance micron scale β-Ti phase plasticized Ti-based bulk amorphous composite; Research amorphous composite material's flow stress and deformation characteristics in the liquid-solid two-phase region, establish the constitutive model of rheological behavior, reveal the microscopic mechanism of the rheological behavior; Research the plastic deformation behavior of rheocasting bulk amorphous composites at room temperature, reveal the microscopic mechanism of tensile plastic deformation. The research will lay the theoretical basis of the bulk amorphous composite rheocasting process control and industrial applications. The endogenous crystal second phase plasticized block amorphous composite can be used as a structural material towards engineering applications, which has great scientific significance.

非晶体基体中通过引入晶体第二相形成块体非晶复合材料是解决非晶材料室温脆性的有效方法，而利用块体非晶复合材料在液固两相区的黏塑流变实现近净成形是解决块体非晶材料成形的新途径。本申请项目以Ti-Zr-(Ni)-Cu-Be-(V, Nb, Mo)体系为研究对象，构建多组元多晶体凝固-塑性变形全过程的相场模型；研究流变铸造条件下非晶复合材料成分设计、组织结构形成规律和控制原理，设计并形成性能优异的微米尺度β-Ti相增塑的Ti基块体非晶复合材料；研究非晶复合材料在液固两相区内的流变应力和变形特点，建立流变行为的本构模型，揭示流变行为的微观机制；研究流变铸造块体非晶复合材料的室温塑性变形行为，揭示拉伸塑性变形的微观机制。研究成果将奠定块体非晶复合材料流变铸造的工艺控制和工业应用的理论基础，对内生晶体第二相增塑块体非晶复合材料能够作为结构材料走向工程应用具有重大科学意义。

本项目主要以Ti-Zr-Cu-Be-V多组员体系为研究对象，采用真空铜模吸铸法制备Ti基非晶复合材料，通过调整合金成分配比，制备了一系列复合材料试样，通过电子显微镜、XRD、DSC、TEM等各项参数检测及理论分析，对比得出以最佳原子配比的材料制备的非晶复合材料具较好的非晶形成能力。基于铸态非晶复合材料塑性较差，采用半固态等温处理提高其塑性，研究表明半固态等温处理在一定处理时间范围内，较铸态复合材料相比，其塑性有极大提高，增长率高达136.17%，经分析其塑性提高主要取决于材料内部原有β-Ti形状变化及非晶基体内衍生晶体相增加了晶体体积分数。通过改变其等温处理温度和等温处理时间等工艺参数，揭示其微观组织转变的规律及转变机理，总结了半固态处理过程中微观组织演变规律：非晶基体相熔化→枝晶臂合并→大块状组织→晶界处局部熔化分离→晶粒组织球化→晶体继续生长→基体相成分不均匀→晶粒异常长大的规律。此外基于材料Ti48Zr18Cu5V12Be17得出了晶体生长动力学模型，通过计算生长指数n，判定了晶粒生长不同阶段的影响因素，860℃半固态等温处理保温10min以内，Ti48Zr18V12Cu5Be17非晶复合材料中β-Ti晶粒生长主要受晶界曲率和晶格扩散共同控制。超过10min，β-Ti晶粒生长主要受晶格扩散和晶界扩散共同控制。. 基于非晶复合材料需实现其使用环境广泛性，还研究了本项目未涉及的采用循环深冷方式探究低温对非晶复合材料微组织结构及力学性能的影响，研究表明循环深冷提高材料的断裂强度。