Novel Al-Ti-Nb-B grain refiners with superior efficiency for Al-Si alloys

Abstract A superior anti Si-poisoning Al-Ti-Nb-B refiner with Ti:Nb=1:4 and M:B = 8:1 (M=Ti, Nb) was developed by a comprehensive data screening on the Al-10Si/Al-Ti-Nb-B system with thermodynamic calculations, by which the refinement level for Al-10Si alloys was upgraded to 109~125 μm, significantly extending the grain size tailoring scope for the aluminum casting industry. The synergistic effect of Ti/Nb not only bestowed an appreciable amount of high-potency aluminides during solidification but also formed NbB2-TiB2 core-shell structure which created an effective diboride substrate for nucleating α-Al. These results shed new lights on designing innovative anti Si-poisoning refiners by composition engineering.