Papers by Keyword: Al-Sr Master Alloy

Abstract: A356 aluminum alloy was modified by Al-Sr master alloy, and the eutectic silicon phase was changed from long needle to short fiber. Compared with the untreated, the secondary dendrite spacing decreased by 14.37 %, the tensile strength increased by 13.0 MPa, and the elongation increased by 29.51 %. After modification treatment, more developed secondary dendrites and block inclusions can be seen in the tensile fracture of A356 alloy, which is not conducive to the plasticity and fatigue resistance of the alloy.

Abstract: In the present work, the influence of Al-Sr and Mg-Sr master alloys on the as-cast microstructure of the AZ31 magnesium alloy was investigated,and the refinement efficiencies of both master alloys were also analyzed and compared. The research results indicate that both the Al-Sr and Mg-Sr master alloys have obvious refinement effect on the as-cast microstructure of the AZ31 magnesium alloy, and the refinement efficiency of the Mg-Sr master alloys was better than that of the Al-Sr master alloys. The mechanisms for the differences of grain refinement efficiency between Al-Sr and Mg-Sr master alloys on the AZ31 magnesium alloys were also discussed.

Abstract: This paper introduces a novel “direct reaction - hot extrusion” technique for producing high effective, fast modification and high Sr content Al-Sr20 master alloy. It mainly contains four processes: 1) Alloying by a medium-frequency induction furnace with complementary mechanical and electromagnetic stirring; 2) Degassing and deslagging by a rotary degassing method; 3) Casting coarse alloy bars; 4) Producing Al-20Sr master alloy wire by using a hot-extrusion process of large cross-section deformation. Microstructural characterizations revealed that the intermetallic Al4Sr phase in the Al-Sr20 alloy was homogeneously distributed in Al matrix with small size and roundish shapes, which ensured the master alloy wire exhibit advantages including high recovery, good reproducibility, no delitescence of modification, no corrosion on equipments, and good workability with smooth surface, no bubbles, no peeling and no cracking. This Al-Sr20 master alloy has been industrially applied in Al-Si alloys casting in automobiles and motorcycle wheels, etc.

Abstract: The influence of Al-10.5%Sr master alloy, which is much cheaper than Mg-Sr master alloys, on the as-cast microstructure of the AZ31 alloy was investigated. The research results revealed that the Al-10.5%Sr master alloy produced obvious modification of the as-cast microstructure of the AZ31 alloy, and the modification efficiency increased with the holding time from 0min to 60min and the amount of Sr from 0.01% to 0.1%. Moreover, the results also showed that the Al-10.5%Sr master alloys of different states had different modification efficiency on the as-cast microstructure of the AZ31 alloy. The Al-10.5%Sr master alloys in extrusion deformation state and rapid solidification state had better modification efficiency than the Al-10.5%Sr master alloys received and in heat treatment state, which could be related to the microstructure of the Al-10.5%Sr master alloys with different states.