A Novel Approach to Improve Conductivity of 1XXX Al Alloy by In Situ Synthesis of Al–X-B Grain Refiner

Transition impurity elements in Al alloys have a significant effect on electrical conductivity. To fulfill the requirements of 3C products, these elements are usually removed by B treatment. Herein, a novel approach was proposed to refine the grain size by in situ synthesis of (Ti,V,Cr,Zr)B₂ particles formed via B treatment. B treatment effectively improved the electrical conductivity of 1060 alloy, which was close to pure Al. The reaction products exhibited higher refining efficiency than traditional Al–5Ti–B grain refiner, which achieved same grain size with only 10 pct addition of latter. The refining mechanism is also elucidated. (Ti,V,Cr,Zr)B₂ can act as nucleation sites owing to the several nanometer-thick Al₃Ti layers on its surface, which are coherent with the α-Al matrix. Unlike TiB₂, (Ti,V,Cr,Zr)B₂ has no orientation relationship with either the α-Al or Al₃Ti layer. Present study may provide a method to reuse impurity elements and guide the development of a superior grain refiner.