选区激光熔化增材制造专用高强度Al-Mg-Sc-Zr合金成分设计及性能调控

传统牌号铝合金粉末床增材制造极易产生冶金缺陷、性能不高、塑性低，已成为长期困扰增材制造在航空航天等轻量化高强度复杂构件应用的技术瓶颈。本项目打破传统铝合金增材制造仅靠细晶强化的单一思路，提出开发基于细晶与纳米析出协同强韧化的SLM专用含钪高强铝合金。本项目在前期已开发出打印态拉伸强度460MPa的Al-Mg-Sc-Zr基础上，从激光熔池易裂的难点出发，通过相图和裂纹敏感因子计算，揭示合金成分对裂纹敏感性的影响机制，结合实验获得抗裂的合金成分区间；在此基础上阐明Sc、Zr等稀土微合金化设计对纳米Al3(Sc,Zr)相析出特征的影响行为，以及晶粒细化机理；探明纳米析出与晶粒细化对增材制造构件强度-塑性协同提升机制，获得拉伸≥530MPa、延伸率≥12%超高强度铝合金成分设计原理，发展具有国际先进水平的粉末床增材制造专用Al-Mg-Sc-Zr合金粉体成分设计、雾化制备及构件成形技术原型。

The additive manufacturing of traditional aluminum alloys usually exhibit metallurgical defects, unfavorable mechanical property and low plasticity, which induce a long-time puzzled technical bottleneck for the application of additive manufacturing in lightweight field, such as aerospace etc. Breaking through the conventional thinking of fine-grain strengthening of additive manufacturing aluminum alloys, this project proposes developing Sc containing aluminum alloys with excellent strength and toughness by synergetic nano-precipitation and fine-grain strengthening. The applicant has already developed Al-Mg-Sc-Zr alloy with tensile strength 460MPa but there exists cracks in printed sample. Based on this difficulty, this project plans to disclose the effecting mechanism of alloy composition on the crack-sensitivity by combinations of calculations of phase diagram and crack-sensitivity and experimental research, then the anti-crack composition is anticipated to be obtained. Based on this basis, the project plan to illuminate the effecting mechanisms of rare earth microalloying, such as Sc, Zr ect on the nano-sized Al3(Sc, Zr) precipitation behavior and the grain refinement mechanism; then clarify the strength and plasticity synergetic improving mechanisms by nano-precipitation and grain refinement, in order to obtain the alloy compositional designing theory of high-strength aluminum alloys with tensile strength exceeding 530MPa and tensile ratio surpassing 12%. Over all, this project will develop prototypes from alloy compositional design, powder atomization preparation to shaping technology with international advanced level for powder-bed additive manufacturing.