Application of Al-2La-1B Grain Refiner to Al-10Si-0.3Mg Casting Alloy
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JMEPEG DOI: 10.1007/s11665-017-2970-6
Application of Al-2La-1B Grain Refiner to Al-10Si-0.3Mg Casting Alloy Lijun Jing, Ye Pan, Tao Lu, Chenlin Li, Jinhong Pi, and Ningyue Sheng (Submitted May 4, 2017; in revised form August 16, 2017) This paper reports the application and microstructure refining effect of an Al-2La-1B grain refiner in Al10Si-0.3Mg casting alloy. Compared with the traditional Al-5Ti-1B refiner, Al-2La-1B refiner shows better performances on the grain refinement of Al-10Si-0.3Mg alloy. Transmission electron microscopy analysis suggests that the crystallite structure features of LaB6 are beneficial to the heterogeneous nucleation of a-Al grains. Regarding the mechanical performances, tensile properties of Al-10Si-0.3Mg casting alloy are prominently improved, due to the refined microstructures. Keywords
aluminum casting alloy, grain refinement, master alloy, tensile properties
1. Introduction In the industrial practices of aluminum–silicon casting alloys, grain refinement and modification are usually employed to obtain fine a-Al grains together with fibrous eutectic Si phases of cast microstructures and to reach the good comprehensive mechanical properties of castings (Ref 1-7). In the previous works, the ternary Al-Ti-B refiners, e.g., Al-5Ti-1B refiner, have been extensively utilized to refine a-Al dendrites in the wrought aluminum alloys, since the heterogeneous nucleation effect with TiB2 and a high growth restriction factor (GRF) of titanium (Ref 8-10). On the other hand, in the casting practices of Al-Si casting alloys, strontium was usually used as modifier, which transforms the eutectic Si phases from a platelike to a fiber-like feature with less fading phenomenon (Ref 11-15). However, the grain refiners with high ratios of Ti: B usually work in a unfavorable refining efficiency in Al-Si casting alloys due to the interaction of Ti with Si, forming titanium silicides, which depletes the effective quantity of Ti elements in the melt of alloys (Ref 16). In addition, a mutual poisoning effect between B and Sr elements, forming SrB6 particles (Ref 17, 18), has been suggested to be responsible for impairing the grain refinement efficacy and modification effect. To eliminate aforementioned mutual poisoning in the Al-Si
Lijun Jing, Ye Pan, Chenlin Li, and Ningyue Sheng, School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, China; Tao Lu, School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, China; and Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing 211167, China; Jinhong Pi, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing 211167, China. Contact e-mails: [email protected], [email protected], and [email protected].
Journal of Materials Engineering and Performance
casting alloys, Bolzoni et al. (Ref 19-21)
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