Browse Publications Technical Papers 2001-01-0420
2001-03-05

Study of Mechanical Properties of Both Magnesium Alloys AZ91D and AM50A Cast by Thixomag® Process Influence of Microstructure 2001-01-0420

The forming of alloys from the liquid state can be realized thanks to various casting technologies where the temperature of the metal is high enough to fill a given die correctly. A variety of casting defects often occur in the final part, such as gas porosity, shrinkage porosity and hot cracking.
In the case of the magnesium foundry, all handling of molten metal requires serious safety precautions to avoid explosion and burning. Protective gas mixtures (SF6, SO2, CO2) are used to minimize the ignition risks but have a bad impact on the environment.
The semi-solid forming operates using a lower temperature in the solidus-liquidus range and seems to be interesting, in particular, for the quality requests of the die caster and for safety and a clean environment.
The purpose of this paper is to present the mechanical results of tensile tests carried out on magnesium standard samples, which are cast by Thixomag® process from the semi-solid state. Two magnesium alloys AZ91D and AM50A are characterized.
The static and dynamic elastic modulus are determined by tensile tests equipped with an extensometer and by an ultrasonic method respectively.
In the case of semi-solid samples, the mechanical properties increase and, in particular, the Young's modulus. The porosity ratio of semi-solid parts is lower than that of conventional parts, cast by conventional process. The microstructure and the X-ray analysis display aluminum segregation between the globular particles and the eutectic phase. The aluminum content is around 20 wt% in the eutectic phase. This means that the aluminum is supersaturated in the eutectic and precipitated discontinuously like thin lamella of Mg17Al12. This is an intermetallic cubic structure.
The size and the shape of globules influence the mechanical properties.
This study confirms the first results announced two years ago on the wiper parts. The presence of Mg17Al12 lamella reinforces the solid solution, having a hexagonal structure, and improves the Young's modulus.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.

Due to current capacity constraints, printed versions of our publications - including standards, technical papers, EDGE Reports, scholarly journal articles, books, and paint chips - may experience shipping delays of up to four to six weeks. We apologize for any inconvenience.
We also recommend:
TECHNICAL PAPER

Ultrasonic Cavitation Based Casting of Aluminum Matrix Nanocomposites for Automobile Structures

2006-01-0290

View Details

TECHNICAL PAPER

Fatigue Properties of High Pressure Die-Cast Magnesium AM60B Alloy

2007-01-0390

View Details

TECHNICAL PAPER

Development and Property Evaluation of Aluminum-Alloy Reinforced with Nano-ZrO2 Metal Matrix Composites (NMMCs) for Automotive Applications

2009-01-0218

View Details

X