Recent Advancements in Creep Resistant Magnesium Alloys and Composites: A Review (original) (raw)

Creep Resistant Magnesium Alloys for Powertrain Applications

Creep resistant magnesium alloys are candidate materials for automotive powertrain applications. Since the 90's, a number of new creep-resistant magnesium alloy systems have been investigated and developed. These are for the most part based on rare-earth, alkaline earth, and silicon additions. This paper gives an overview of creep resistance in magnesium and a review of creep resistant magnesium alloys for power-train applications.

Status of the Development of Creep Resistant Magnesium Materials for Automotive Applications

Thermec 2009, Pts 1-4, 2010

The present paper presents the development status of creep resistant magnesium materials. It reviews the creep deformation mechanisms of magnesium alloys. Based on these mechanisms, several effective approaches to improve the creep resistance are discussed, including alloying, microstructural control and the development of new monolithic alloys and composites.

Newly developed magnesium alloys for powertrain applications

JOM, 2003

Several new magnesium alloys have been developed recently for hightemperature applications to obtain an optimal combination of die castability, creep resistance, mechanical properties, corrosion performance, and affordability. Unfortunately, it is diffi cult to achieve an adequate combination of properties and, in fact, most of the new alloys can only partially meet the required performance and cost. The ZE41 alloy, which is used for most gravity-casting applications, has moderate strength and creep resistance combined with good castability. Although this alloy exhibits poor corrosion resistance, it is still preferred for certain applications.

Magnesium and Its Alloys in Automotive Applications – A Review

Magnesium is very attractive material as it has the combination of good strength, low weight and good quality. The usage of magnesium and its alloys has considerably increased over the past ten years. In structural applications, where weight plays a major role, magnesium is a good choice. Its recyclability property also gives an edge. The use of magnesium and its alloys in automotive components was limited in the early sixties and seventies but today the awareness on fuel savings and environmental protection through reduced CO2 emissions makes this material attractive. This paper reviews the benefits due to Mg, its alloy materials, manufacturing methods and applications in automotive sector. It also summarizes directions for the development of new magnesium alloys based on properties.

AUTOMOTIVE APPLICATIONS OF MAGNESIUM AND ITS ALLOYS

Today's interest in magnesium alloys for automotive applications is based on the combination of high strength properties and low density. For this reason magnesium alloys are very attractive as structural materials in all applications where weight savings are of great concern. In automotive applications weight reduction will improve the performance of a vehicle by reducing the rolling resistance and energy of acceleration, thus reducing the fuel consumption and moreover a reduction of the greenhouse gas CO 2 can be achieved.

Interrupted creep behaviour of Mg alloys developed for powertrain applications

Materials Science and Engineering: A, 2010

A conventional magnesium alloy, AZ91D, and two creep resistant magnesium alloys, developed for powertrain applications, MRI 153M and MRI 230D, are prepared by high pressure die casting. These alloys are tested for their creep behaviour in the continuous manner, as is the current practice, and in the interrupted manner, which represents the real life situation more closely. It is observed that the interrupted creep tests give rise to a primary creep appearing at the beginning of each cycle resulting in a higher average strain rate than that encountered in the continuous creep tests. Further, the shorter the cycle time, higher is the average strain rate in the interrupted creep tests. A higher average strain rate will give rise to a higher strain over the same period. This is attributed to the recovery taking place during the cooling and heating between two cycles. The effect of additional precipitation during interrupted creep tests depends on the nature of the precipitates. The additional precipitation of ␤ phase during the cooling and heating between two cycles increases the steady state strain rate in the AZ91D and MRI 153M alloys, whereas the additional precipitation of C36 phase during the cooling and heating between two cycles decreases the steady state strain rate in the MRI 230D alloy.

Magnesium alloy applications in automotive structures

JOM Journal of the …, 2008

The use of magnesium alloys in structural applications has great potential for the lightweighting of transportation vehicles. Research within the CAST Cooperative Research Centre has tackled some of the important issues related to the use of magnesium in structural applications. To this end, a new alloy with extrudability and properties similar to 6000 series aluminum alloys has been developed. Furthermore, a method of laser heating magnesium alloys before self-piercing riveting has enabled high-integrity joining between magnesium components or between magnesium and dissimilar metals. In this paper, new technologies and improved understanding of the deformation behavior of wrought magnesium alloys are discussed in light of key metallurgical features such as alloy composition, grain size, and work hardening rate. All are part of CAST Co-operative Research Centre. Dr Easton can be reached at mark.easton@ eng.monash.edu.au.

Creep resistance in magnesium alloys and their composites

International Journal of Materials & Product Technology, 2003

A considerable improvement in the creep properties of magnesium alloys can be potentially achieved by non-metallic reinforcement (metal matrix compositesÐMMCs). This paper provides a comparative report on experiments which were conducted on the two representative magnesium alloys (AZ91 and QE22) and their composites in order to evaluate the creep properties and to clarify the direct and indirect strengthening effects of reinforcement in creep. A comparison between the creep characteristics of squeeze-cast AZ91 and QE22 magnesium alloys reinforced with 20 vol.% Al 2 O 3 short fibres and unreinforced matrix alloys shows that the creep resistance of the reinforced materials is considerably improved compared to the monolithic alloys. By contrast, the investigations of the creep behaviour of a particulate QE22-15 vol.% SiC composite prepared by powder metallurgy and the squeeze-cast hybrid QE22 matrix composites have revealed no substantial increase in the creep strength of the composite compared to the matrix alloy and AZ91 matrix composites. These results indicate a paramount importance of the choice of the composite matrix alloy and the reinforcement used.