等通道变形Al-B中间合金组织及细化效果_金属材料工程.rar

摘要：Al-B中间合金是一种良好的细化剂，在熔炼铝时可以细化晶粒，但是Al-B合金中AlB2通常是粗大的长条状，导致细化能力受到限制。本文以Al-B中间合金作为研究对象，对Al-B中间合金进行等通道挤压（ECAP），研究经1、2、4、6、8变形道次后Al-B中间合金的显微组织、显微硬度、电导率的变化，以及将ECAP变形Al-B中间合金作为细化剂添加到纯铝中，并观察不同道次的Al-B中间合金对纯铝的细化效果。研究结果表明：随着挤压道次的增加，Al-B中间合金的显微组织由粗大的长杆状逐渐破碎为细小的颗粒状。Al-B合金的显微硬度经等通道变形后明显增加，由铸态的31.02Hv增加到2道次时的50.38Hv，4道次后有所降低，但是变化不大，趋于稳定。Al-B中间合金的电导率随着挤压道次的增加逐渐下降。

　　　纯铝的宏观组织大多为粗大的柱状晶，中心等轴晶较少且比较粗大。加入ECAP变形Al-B合金后，中心等轴晶区逐渐扩大且晶粒细小，粗大的柱状晶区缩小且变细。加入6道次ECAP变形Al-B合金后，中心等轴晶区最大，晶粒最细小。随着Al-B合金变形道次的增加，显微硬度逐渐增大，但是8道次时，显微硬度较低。不同道次ECAP变形Al-B合金细化的纯铝的电导率呈现波动性变化。

关键词：ECAP；Al-B中间合金；显微组织；性能；细化效果

Abstract:Al-B master alloy is a good refiner, it can refine aluminum grains in the aluminum melting. In Al-B master alloy, AlB2 is usually a long rod-shaped, so its refining ability is limited. In present work, Al-B master alloy is used for studying. After equal channel angular pressing (ECAP), the material microstructure, mechanical properties, and the conductivity of Al-B master alloys were studied, and observed the refinement. The results show that the microstructure of Al-B master alloy is gradually broken by the thick long rod-shaped small granular with the increase of ECAP passes. After equal channel deformation, the hardness of Al-B master alloy increase obviously, increased by 31.02Hv for the cast to 50.38Hv for 2 pass, then reduce after 4 pass, but little change in the stabilized. The conductivity of the Al-B master alloy is decreasing with the increase of ECAP passes.

     The microstructures of pure aluminum are mostly coarse grains, the equiaxed grains in the center are less and thick. After adding Al-B master alloy, the range of equiaxed grains expand and the grains are small. The range of coarse columnar grains reduces and the grains become thinner. When adding ECAP Al-B master alloy of 6 pass, the range of equiaxed grains is the largest and the grains are smallest. With the increase of ECAP passes, the hardness of Al-B master alloy gradually increase, but the hardness of 8 pass is lower. The refinement of the Al-B master alloys after different deformations changes without regularity.

Keywords: ECAP; Al-B master alloy; microstructure; properties; refinement