Effects of Si content on the microstructure and tensile strength of an in situ Al/Mg 2 Si composite
- PDF / 1,011,442 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 25 Downloads / 195 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Effects of Si content on the microstructure and tensile strength of an in situ Al兾兾Mg2 Si composite Jian Zhang, Yu-qing Wang, and Bing Yang Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China
Ben-lian Zhou Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, and International Center for Material Physics, Chinese Academy of Sciences, Shenyang 110015, China (Received 4 August 1997; accepted 3 April 1998)
Al兾Mg2 Si composites were in situ fabricated by the usual die-casting technique, and effects of the Si contents in the composites on microstructures and tensile strengths were investigated. Experimental results show that extra Si contents in Al兾Mg2 Si composites induce a ductile matrix and a uniform distribution of in situ particles. The refined microstructures lead to an obvious increase in both strength and ductility of the metal matrix composites (MMCs). The effects of extra Si on both the solidification process and fracture characteristics of the Al兾Mg2 Si composites were analyzed.
I. INTRODUCTION
Over the past few years, efforts are underway on both industrial and academic fronts to develop particulate reinforced metal matrix composites (PMMCs). Among the numerous methods of producing discontinuously reinforced metal matrix composites (MMCs), an in situ process produces the thermodynamically stable systems based on the in situ nucleation and growth of the reinforcements from the parent matrix. The simple technical process and optimized interface of the in situ MMCs have attracted considerable attention recently.1 Among the particulate reinforcements that are commonly used in Al, Mg, or Ti matrix, Mg2 Si shows the lowest density. Table I lists some physical and mechanical properties of Mg2 Si and Si. This has made the MMCs with Mg2 Si reinforcement attractive substitute materials of conventional Al兾Si alloys for automotive or other applications. The in situ composite using Mg2 Si as a reinforcing phase in Mg matrix was investigated.2,3 The strengths of these materials were comparable to those Al兾Si alloys at room temperature, while higher at elevated temperatures. Mabuchi and Higashi reported the strengthening mechanisms of the in situ Mg兾Mg2 Si composites prepared by rapid solidification (RS) and hot extrusion (HE) of Mg–Si alloys.4 Other publications focused on the mechanical properties of Mg兾Mg2 Si composites5–7 and Mg–Si alloys8 prepared by RS, HE, or powder metallurgical process. Unfortunately, the most practical studies on the casting process of Mg2 Si reinforced MMCs have not received adequate attention. Moreover, formal reports on Al兾Mg2 Si PMMCs have not been found yet. There exists a pseudobinary section between Al and Mg2 Si in the Al–Mg–Si system. The solidus tempera68
http://journals.cambridge.org
J. Mater. Res., Vol. 14, No. 1, Jan 1999
Downloaded: 26 Dec 2014
ture in the pseudobinary system is constant at the eutectic temperature of 595 ±C,9 and the eutectic composition was reported to be Al –8.2
Data Loading...
