Abstract Microgravity solidification provides a particular opportunity to produce an extraordinary microstructure and optimized mechanical properties. To shed further light on the influence of rapid solidification mechanism on mechanical properties, both the microgravity solidification mechanism and resultant micromechanical properties of ternary Al 57 Ag 12 Ge 31 alloy were analyzed by means of drop tube, nanoindentation and frictional sliding techniques, which was compared with equilibrium solidification condition. The solidification pathways changed with the decrease of droplet size, owing to a larger cooling rate and a higher undercooling. Consequently, the microstructure transformed from dendrites plus two-phase eutectic to two-phase eutectics, eventually to anomalous ternary eutectic, while the thickness of surface (Ge) layer decreased. The micromechanical properties of rapidly solidified alloy droplets were evidently improved with the decrease of droplet size, which is mainly ascribed to the microstructure refinement and the homogenous distribution especially of hardening (Ge) phase. The measured microhardness, yield strength, strain hardening exponent, pile-up resistance and friction coefficient were analyzed as a function of droplet size.

中文翻译：

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微重力条件下凝固的三元Al Ag Ge合金的结构演化和微观力学性能

摘要 微重力凝固为产生非凡的微观结构和优化的机械性能提供了一个特殊的机会。为进一步阐明快速凝固机制对力学性能的影响，通过滴管、纳米压痕和摩擦滑动技术分析了三元Al 57 Ag 12 Ge 31 合金的微重力凝固机制和所得微观力学性能，并进行了比较。具有平衡凝固条件。由于较大的冷却速率和较高的过冷度，凝固路径随着液滴尺寸的减小而改变。因此，组织从枝晶加两相共晶转变为两相共晶，最终转变为异常三元共晶，而表面（Ge）层厚度减小。快速凝固合金液滴的微观力学性能随着液滴尺寸的减小而显着提高，这主要归因于组织细化和均匀分布，特别是硬化（Ge）相。测量的显微硬度、屈服强度、应变硬化指数、堆积阻力和摩擦系数作为液滴尺寸的函数进行分析。