# Applications of Magnesium and Its Alloys: A Review
## 3 Magnesium and Its Alloys as an Engineering Material
### Engineering Applications
#### 3.2.2 Automotive Applications  
The earliest automotive applications of magnesium and its alloys can be traced back to 1918, where magnesium-based racing engine pistons for the Indy 500 were introduced [52]. However, it was not until the 1930s when Volkswagen outfitted a magnesium-based engine block for its Beetle series that set off a widespread adoption of magnesium in the automotive industry [8]. Since then, magnesium has been used for various powertrain, chassis, and body structure applications. Today, magnesium remains the third most used metallic material in the automotive industry [10]. Figure 2 provides a pictorial summary of the contemporary automobile components constructed with magnesium and its alloys.  
In many ways, the growth story of magnesium applications for the automotive industry is similar to the aerospace industry. Firstly, due to its inherent limitations, it is mainly adopted for its \"in-use\" benefits. Hence, despite having many automotive applications, its overall share of metallic materials in the automotive industry remains minuscule compared to steel and aluminum [10]. However, given the industry's increased pressure by authorities and the wider community to reduce its emissions and pursue a more sustainable pattern of growth, magnesium has increasingly garnered attention for its potential to reduce the vehicle's weight, provide energy savings, and limit environmental impact without compromising its overall strength and functions [32]. This fueled industry and research interest in magnesium. It also contributed to a surge in its adoption in the automotive industry even though it comes with a higher price point than other conventional metallic materials.  
Presently, cast magnesium alloys remain the most used type for automotive applications due to their excellent characteristics. In addition, there have also been progress and several developments in casting fill and solidification, which enabled the production of a broader and higher quality range of cast products. Cast magnesium alloy applications include instrument panel structures, cross-car beams, roof frames, seat frames, and more. Noticeably, they tend to be located in automobiles' front and top portions, where weight reduction is essential [10]. The dominant types of cast magnesium alloys in the automotive industry include the Mg-Al-based alloy series, such as the AZ and AM alloys; Mg-rare earth-based alloys, e.g., WE43 and E21; and ZK alloys.  
Furthermore, for applications requiring elevated temperatures, high-strength magnesium alloys and alloy nanocomposites can be considered as they possess superior thermal and dimensional stabilities [55]. However, apart from cast magnesium alloys, other types of magnesium and its alloys--e.g., sheet magnesium and extruded magnesium--seemed to have limited to no reported applications in the modern automotive industry. Several materials, processes, and performance challenges plaguing magnesium need to be resolved to drive greater magnesium uptake in the automotive industry [10].