Study on the Interaction of Rare Earth (La) and Strontium with Titanium and Boron in the Al-Ti-B based master alloy

摘要

Al-Ti-B-Sr-RE master alloys were prepared firstly by the reaction of complex halide salts with molten aluminum at 800°C, and then the addition of Al-RE and Al-Sr master alloys into the melt. The constituent phase and microstructure were characterized by XRD, optical microscope (OM) and scanning electron microscope (SEM). The element content was analyzed by spectrometer, X-ray fluorescence spectrometry and electron probe microscope. Ti_2Al_(20)RE, SrB_6, LaB_6, Al_4Sr and Al_(11)La_3 are the constituent phases in these master alloys. The constituent phases containing Sr and RE in the Al-Ti-B master alloy depend on the ratio of Ti and B. The critical ratio of Ti and B is 2.2:1. Obviously, SrB_6 and LaB_6 phases are the reaction products of AlB_2 with Sr or La during master alloy fabrication. The two layer lump-like Ti-Al-RE particles formation mechanism is proposed.