超声振动法制备半固态TiAl3/A356复合材料浆料的微观组织演变

Microstructure evolution of semi-solid TiAl3/A356 composite prepared by ultrasonic vibration

摘要:

本文利用超声振动法制备半固态TiAl3/A356铝基复合材料浆料，利用扫描电镜和X射线衍射技术研究了超声温度，超声时间和超声功率对半固态TiAl3/A356铝基复合材料浆料的微观组织的影响。结果显示，初生α-Al颗粒的尺寸随着超声温度和超声功率的降低而减小；而随着超声时间的增加，先减小后增大。当超声温度为608 ℃、超声功率为1000 W、超声时间为60 s时，获得的半固态浆料组织中的初生α-Al颗粒形貌较为理想，平均初生α-Al颗粒尺寸为62 μm，形状系数为0.8。微观组织演变的机理是空化效应和声流效应引起的形核率和过冷度的增加。此外，原位生成的TiAl3颗粒有很强的结合α-Al颗粒的能力。

关键词:微观组织;半固态;铝基复合材料;超声振动;初生α-Al颗粒

Abstract:

The semi-solid TiAl3/A356 aluminum composite was prepared by ultrasonic vibration treatment(UVT). The effects of UVT temperature, time and power on the microstructure of semi-solid slurry of TiAl3/A356 composite were studied by using SEM and X-ray diffraction techniques. The results revealed that the size of primary α-Al particles increased with the decrease of UVT temperature and power. The size of primary α-Al particles decreased at first and then increased with the increase of UVT time. When treated for 60s at an UVT temperature of 608 ℃ and an UVT power of 1KW, a good primary α-Al particle morphology with an average size of 62 μm and a shape coefficient of 0.8 could be obtained. The mechanism involved in the development of microstructure is the result of increase of nucleation rate and undercooling caused by a cavitation and acoustic streaming. Furthermore, the in situ TiAl3 particles have strong ability to nucleate α-Al particles.

Key words:microstructure; semi-solid; aluminum matrix composite; ultrasonic vibration; primary α-Al particles