Al-4.99Zr-1.1B合金的显微组织及其对AZ31镁合金的晶粒细化作用(英文)

Microstructure of Al-4.99Zr-1.1B Master Alloy and Its Grain Refinement Effect on AZ31 Magnesium Alloy

采用K2Zr F4、KBF4混合粉末与铝熔体原位合成方法制备了Al-4.99Zr-1.1B合金,利用X射线衍射仪、光学显微镜和扫描电镜,研究了Al-4.99Zr-1.1B合金的显微组织及其对AZ31镁合金的晶粒细化作用。结果表明:Al-4.99Zr-1.1B合金中含有大量细小的Zr B2粒子。随着Al-4.99Zr-1.1B合金添加量的增加,AZ31镁合金的α-Mg晶粒逐渐细化,晶间β-Mg17Al12相从网状转变成细小块状。添加0.6%的Al-4.99Zr-1.1B合金,可使AZ31镁合金的α-Mg晶粒从170μm细化到45μm。Zr B2粒子作为α-Mg晶粒的异质形核核心使α-Mg晶粒得到细化。

An A1-4.99Zr-l.lB master alloy was fabricated by in-situ synthesis from A1 melt and K2ZrF4＋KBF4 mixed powder. The microstructure of the A1-4.99Zr-1.1B master alloy and its grain refinement effect on AZ31 magnesium alloy were studied by XRD, OM, SEM and EDS. Results show that a large number of fine ZrB2 particles can be observed in the A1-4.99Zr-l.lB master alloy. With increasing the addition amount of A1-4.99Zr-1.1B master alloy, the primary α-Mg grains of AZ31 magnesium alloy are further refined and the network structure of the intermetallic fl-MglTAll2 phase is changed into small blocky structure. Upon adding 0.6% AI-4.99Zr-1.1B master alloy, the average size of primary α-Mg grains is reduced from 170 μm to 45 μm. The present results indicate that the ZrB2 particles can act as the effective heterogeneous nuclei of α-Mg grains and is responsible for the grain refinement of AZ3 l magnesium alloy.