Study On The Preparation Of Al-RE-B Refiner And Its Refinement Effect

In recent years,the new energy automobile industry in my country is developing rapidly,and the performance requirements of the high-performance power battery industry on the aluminum electrode foils have also become higher and higher.Al-Ti-B alloy is the most common refiner in wrought aluminum alloys.It has excellent performance in microstructure refinement,but the existence of Ti has fatal damage to electrical conductivity.For this reason,this subject is trying to develop a new type of Al-RE-B master alloy refiner to help deformed aluminum alloy materials to obtain a fine and uniform grain structure,which can meet the requirements of subsequent deep processing without damaging its performance of electrical and thermal conductivity.The research results show that the high-quality Al-La-B refiner should have the structure characteristics of the refined particle phase coexisting with the surplus rare earth phase,and the refined particles are fine and uniformly dispersed.The refining mechanism is that the surplus La increases the compositional undercooling and La B₆ provide the synergy of heterogeneous nucleation particles.Al-5La-B refiner contains Al₁₁La₃ phase and La B₆ phase,and its refinement ability and refinement efficiency in industrial pure aluminum are significantly better than Al-2La-B refiner containing only single La B₆ phase.And the control efficiency and stability for improving the uniformity of the structure are higher,and the performance is more excellent for improving the electrical and thermal conductivity of the aluminum alloy matrix.For the refinement of the as-cast grain structure,the optimal addition amount of Al-5La-B refiner is 0.1wt.%(La,La B₆),the corresponding grain size can be reduced from 1542?m to 185?m,and the refinement range is as high as 88.0%;for the refinement of the recrystallized grain structure,with the increase in the amount of Al-5La-B refiner,the size of the recrystallized grains shows a monotonous decrease;the refinement effect of Al-5La-B refiner has a certain long-lasting effect,and the refinement effect is the best when it is kept for10 minutes.However,if the holding time(?80min)is too long,the refinement effect will obviously decline.The refining effect of Al-5La-B refining agent can be equivalent to that of Al-5Ti-B refining agent,but in terms of the influence on electrical conductivity and thermal conductivity,Al-5La-B refining agent not only does not damage the conductivity of pure aluminum,but can significantly reduce resistance and increase conductivity,which is obviously better than Al-5Ti-B refining agent.The electrical conductivity and thermal conductivity of industrial pure aluminum in the recrystallized state are 57.28%IACS and205.82W/m·K,respectively;when 0.06wt.%(La,La B₆)Al-5La-B refiner is added,its electrical conductivity and thermal conductivity have been greatly improved to 61.55%IACS and 211.34W/m·K,respectively,and the increase is 7.45%and 2.68%,respectively;when adding 0.06wt.%(Ti,Ti B₂)Al-5Ti-B refiner,its electrical conductivity and thermal conductivity are reduced to 54.57%IACS and 203.17W/m·K,respectively,and the reduction range is 4.73%and 1.29%,respectively.