Microstructure specific process chain design for the manufacturing of Al-Li-strips by means of twin-roll casting

铝锂合金的性能优于传统铝合金，因此在航空航天领域具有广泛的应用前景。它们的特殊性能归因于在铝基体中形成了精细分散的非平衡富锂相。铝锂合金的主要问题是各向异性行为和有限的成形性。造成这种现象的主要原因是在直接冷却或模铸及后续的热机械加工（TMP）过程中形成的强化相、晶粒组织和晶体织构的特定特征。由于常规制备合金的潜力有限，必须采用合金化学适应、新型铸造和TMP技术来改善铝锂合金的成形性，同时保持其高比强度。富Mg和Cu的析出相进一步强化了Al-Li合金，而含Sc和Zr的析出相则稳定了Al-Li合金的细晶组织。双辊铸造（TRC）和TMP（包括热不对称轧制）的结合将用于在过饱和al基体中提供宏观均匀分布的合金元素，以创建有益的晶体学织构，设计晶粒微观结构和析出相的大小和形态，并提高材料的成形性。该项目的主要目的是建立高强度Al-Li-Mg-Cu-Sc-Zr合金薄带在TRC期间的加工条件与后续TMP之间的相关性及其显微组织特征和力学性能。

Al-Li alloys are attractive for aircraft and aerospace applications because their properties are superior to those of conventional Al alloys. Their exceptional properties are attributed to the formation of a finely dispersed non-equilibrium Li-rich phase in the Al-matrix. The main issue of Al-Li alloys is an anisotropic behaviour accompanied by a limited formability. The main reasons for this are the specific features of the strengthening phases, the grain microstructure and the crystallographic texture, which are formed during direct chill or mould casting and subsequent thermomechanical processing (TMP). Since the potential of conventionally prepared alloys is limited, methods of alloy chemistry adaptation, novel casting and TMP techniques have to be applied to improve the formability of Al-Li alloys while maintaining their high specific strength. Precipitates rich in Mg and Cu further strengthen the Al-Li alloy, while the fine-grained microstructure will be stabilised by precipitates of Sc and Zr containing particles. The combination of twin-roll casting (TRC) and TMP - including hot asymmetric rolling - will be used to provide a macroscopic homogeneous distribution of alloying elements in a supersaturated Al-matrix, to create a beneficial crystallographic texture, to engineer the grain microstructure and the size and morphology of the precipitates, and to enhance the formability of the material. The main objective of the project is to establish correlations between the processing conditions during TRC and the subsequent TMP of thin strips of high-strength Al-Li-Mg-Cu-Sc-Zr alloys and their microstructural characteristics as well as the mechanical properties.