小变形条件下的扩散焊界面物理与结合机制

扩散焊增材制造(DB-AM)是扩散焊新的应用增长点，非常适合内流道结构实体制造，如航天层板喷注器，核能微通道换热器等。然而，DB-AM要求接头轴向变形量由5%控制到1%，这对扩散焊质量控制提出了挑战，需在工艺理论上更新、完善。分4个研究内容：通过①工艺参数特征参量表征，建立②工艺参数的归一化模型，指导建立扩散焊工艺窗口与工艺设计数据库；进而关注③界面原子键合与晶界迁移机制，研究界面物理，获得界面结合机制。最后支撑④小变形下的扩散焊工艺设计。从而完成小变形条件下的扩散焊界面物理与结合机制研究。提出了扩散焊工艺参数归一化表征和表面去膜机理两个科学问题。其中，由“特征参量”研究切入，将扩散焊热成形工艺参数与材料物理、性能联系起来；再通过足够材料样本修订归一化模型，获得共性及个性知识，是二个研究特色。研究结果是构建扩散焊工艺参数普适性设计理论、数据库与操作窗口，为扩散焊质量提升与控制提供理论支撑。

Diffusion Bonding – Additive Manufacturing (DB-AM) applies diffusion bonding technique in forming of solid structures with hollow channels, such as platelet injector applied in space thrustor, microchannel heat exchanger in nuclear power and so on. However, DB-AM requires the axial deformation of the joint to be controlled from 5% to within 1%, which challenges the quality control in diffusion bonding formation. Thus, it is necessary to improve and update the processing theory. This project assigns 4 phases of research contents as (i) characterization of featured variables for processing parameters, based on which (ii) normalized model for processing parameters will be constructed; Thereafter, the research comes into (iii) interfacial physics to reveal mechanism of interfacial bonding and grain boundary migration; The research above will support (iv) processing design of diffusion bonding at small distortion and consequently carries out the project. Two scientific questions are isolated as characterization models of processing parameters normalization, and cover layer removal mechanism. The research methodology is featured as correlating the hot processing parameters of diffusion bonding with material physics and properties by the introduction of featured variables. Sufficient samples are employed to revise the normalized model to achieve common and characteristic knowledge of the parameters for different materials used in diffusion bonding. The research would contribute common theory of diffusion bonding in design of processing parameters including data base and operation window, which will theoretically support the joint quality promotion and control.