Microstructure and property of rheocasting AZ91 slurry produced via ultrasonic vibration process

• Published in: Transactions of Nonferrous Metals Society of China Vol. 24; no. 3; pp. 619 - 625
• Main Authors: YAO, Jun-ping, SUN, Zhong, YANG, Tao, BBUSHAN, Bharat, LONG, Wen-yuan, ZHANG, Lei
• Format: Journal Article
• Language: English
• Published: 01.03.2014
• Subjects: Casting alloys; Die casting; Die castings; Foundry practice; Magnesium base alloys; Rheocasting; Semisolids; Slurries
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(14)63103-4

The microstructure and mechanical properties of rheocasting AZ91 magnesium alloy were investigated. The semisolid slurry of this alloy was prepared by ultrasonic vibration (USV) process and then shaped by high pressure diecasting (HPDC). The results show that fine and spherical alpha -Mg particles were obtained by USV at the nucleation stage, which was mainly attributed to the cavitation and acoustic streaming induced by the USV. Extending USV treatment time increased the solid volume fraction and average particle size, the shape factors were nearly the same, about 0.7. Excellent semisolid slurry of AZ91 magnesium alloy could be obtained within 6 min by USV near its liquidus temperature. The rheo-HPDC samples treated by USV for 6 min had the maximum ultimate tensile strength and elongation, which were 248 MPa and 7.4%, respectively. It was also found that the ductile fracture mode prevailed in the rheocasting AZ91 magnesium alloy.