熔体超声处理温度区间对镁合金凝固组织的影响  

Effect of Ultrasonic Treatment Temperature Ranges on Solidification Microstructure of Magnesium Alloy

作　　者：李克[1] 高挺[1] 毕秋[1] 罗沛兰[1] 饶磊[1] 

机构地区：[1]南昌大学机电工程学院,江西南昌330031

出　　处：《铸造技术》2010年第3期320-324,共5页Foundry Technology

基　　金：江西省自然科学基金(0650090)

摘　　要：在镁合金的凝固过程中,分别采取液相线以上处理、液相线以下处理和连续处理三种方式进行熔体超声处理,研究不同温度区间内超声作用下凝固组织的细化机制。实验结果表明:声空化的过冷形核作用可降低起始形核温度、提高形核率和凝固速度,声流的搅拌作用则可使温度场均匀,加快结晶潜热的释放,从而细化初生α-Mg晶粒。连续处理方式在超声的有效作用温度范围内全程进行处理,其细化效果优于液相线以上和液相线以下处理方式,可将AZ91D镁合金的平均晶粒尺寸由220μm降至约51μm,AZ31B镁合金的平均晶粒尺寸由300μm降至约113μm。The refinement mechanism of Mg-based alloy under ultrasonic treatment is investigated by introducing the ultrasonic vibration into the magnesium alloy melt with three different temperature ranges, i. e, processing above the liquidus temperature, below the liquidus temperature and continuous treatment. Experimental results show that the ultrasonic vibration results in cavitationinduced undercooling nucleation, which play an important role in refining primary α-Mg by decreasing nucleation temperature, enhancing nucleation rate and cooling rate. The temperature field can be uniformly distributed and the latent heat will be released quickly by stirring the melt with acoustic streaming. The average grain size was reduced from 220 μm to 51 μm for AZ91D alloy and 300μm to 113 μm for AZ31B alloy with continuous ultrasonic treatment, which is more effective than of treating above or below the liquidus temperatures.

关 键 词：镁合金 超声处理 晶粒细化 温度区间 

分 类 号：TG27[金属学及工艺—铸造]