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Abstract The current chip-level Au-Sn solder production process is very complex, to simplify the process while improving the quality of the solder, Au-20Sn solder ribbon was prepared by single-roll rapid solidification technology. The microstructure evolution, composition distribution, phase composition, melting characteristics, wettability and mechanical properties of the solder were studied. The rapidly solidified Au-20Sn solder alloy consisted of a small amount of primary ζ′-Au5Sn dendrites and eutectic structure (ζ′-Au5Sn+δ-AuSn). The microstructure was refined and the components were evenly distributed, while no new phase was formed during the annealing. With Sn element diffused into the δ-AuSn phase from the ζ′-Au5Sn phase, the ζ′-Au5Sn phase was decomposed and the δ-AuSn phase grew up and distributed in the matrix. After rolling, the δ-AuSn phase was elongated along the elongation direction of the ribbon, and the elements were further segregated. Ultimately, compared to the cast-rolling Au-20Sn solder, the melting range was narrower, and the wettability and the shear strength of the solder joint improved. Highlights • Au-20Sn solder was prepared by single-roll rapid solidification technology. • The primary phase of rapidly solidified Au-20Sn was obviously refined. • The refinement mechanism of rapidly solidified Au-20Sn solder is proposed. • The primary phase completely decomposed after suitable annealing process. • The properties of rapid solidification-rolling Au-20Sn solder were improved. [ABSTRACT FROM AUTHOR]

A novel and simple method for preparing Mg–50%Al 4 C 3 (hereafter in wt.%) master alloy has been developed by powder in-situ synthesis process under argon atmosphere. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) results show the existence of Al 4 C 3 particles in this master alloy. After adding 1.8% Mg–50%Al 4 C 3 master alloy, the average grain size of α-Mg decreased from 360 μm to 154 μm. Based on the DTA test results and calculation of the planar disregistry between Al 4 C 3 and α-Mg, Al 4 C 3 particles located in the central regions of magnesium grains can act as the heterogeneous nucleus of primary α-Mg phase. [ABSTRACT FROM AUTHOR]