Microstructure and Mechanical Properties of Aluminum-Alumina Bulk Nanocomposite Produced by a Novel Two-Step Ultrasonic Casting Technique

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• 作者：H. M. Vishwanatha ; Jayakumar Eravelly…
• 刊名：Metallurgical and Materials Transactions A
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：47
• 期：11
• 页码：5630-5640
• 全文大小：3,320 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Materials Science
  Metallic Materials
  Structural Materials
  Physical Chemistry
  Ceramics,Glass,Composites,Natural Materials
  
• 出版者：Springer Boston
• ISSN：1543-1940
• 卷排序：47

文摘

An unprecedented uniform distribution of nano-dispersoids in aluminum-alumina bulk nanocomposite and enhancement in mechanical properties were achieved through a novel ultrasonic casting technique involving two-step ultrasonication. Ultrasonic casting can be classified into two types: (a) contact type, in which the sonicating probe is in direct contact with the liquid melt during ultrasonication and (b) non-contact type, in which the ultrasonic waves reach the liquid melt through the mold wall. Each of the processes has certain disadvantages, and the present study aims at eliminating the primary disadvantages of both the processes, through a novel two-step ultrasonic casting technique. The significant improvement in distribution was possibly due to the cavitation in the mold, leading to the elimination of non-uniformity in the cooling rate at the mesoscopic scale. The improvement in mechanical properties is explained through microstructure analysis in correlation with EBSD analysis, TEM analysis, hardness test, and tensile test. The yield strength of the nanocomposite produced by the two-step process was ~38 pct higher than that produced by non-contact and contact methods.