BOOK_CONTENT
From Manufacturing Technology for Aerospace Structural Materials

Overview

Considering their location on the periodic table of elements, one would think that both magnesium and beryllium would play major roles as aerospace structural materials. However, both of these extremely lightweight metals have serious limitations that make them only minor players. Magnesium alloys usually compete with aluminum alloys for structural applications. Compared to high strength aluminum alloys, magnesium alloys are not as strong (tensile strength of 20 50 ksi vs. 40 80 ksi) and have a lower modulus of elasticity (6.5 msi vs. 10 11 msi). However, magnesium is significantly lighter (0.063 vs. 0.100lb/in 3) and therefore its alloys are competitive on a specific strength and modulus basis. Magnesium alloys, with their hexagonal close-packed structure, must usually be formed at elevated temperatures, while aluminum can be readily formed at room temperature. In addition, magnesium alloys are normally more expensive than comparable aluminum alloys. However, the biggest obstacle to the use of magnesium alloys is their extremely poor corrosion resistance. Magnesium occupies the highest anodic position on the galvanic series, and, as such, there is always the strong potential for corrosion as shown in the example of Fig. 3.1. However, some of the newer alloys have much better corrosion resistance than the older alloys. As shown in Fig. 3.2, some of the newer cast alloys approach the corrosion resistance of competing aluminum casting alloys. Magnesium alloys do have very good damping capacity and castings have found application in high vibration environments, such as helicopter gear boxes. [1]


Figure 3.1: Severely Corroded Magnesium...
Copyright Elsevier Ltd. 2006 under license agreement with Books24x7

Products & Services
Magnesium and Magnesium Alloys
Magnesium and magnesium alloys are nonferrous metals with low density, good ductility, moderate strength, and good corrosion resistance.
Light Alloys and Metals
Light alloys and light metals have low density and high strength-to-weight ratios. Light weight metals include aluminum, magnesium, titanium, and beryllium alloys.
Aluminum and Aluminum Alloys
Aluminum and aluminum alloys are lightweight, non-ferrous metals with good corrosion resistance, ductility, and strength.
Nonferrous Metals and Alloys
Nonferrous metals and alloys are non-iron-based metals or alloys used for a wide range of applications.
Anodes
Anodes are consumables used in a variety of electrochemical processes such as corrosion protection (sacrificial anodes) and electroplating (plating anodes).

Topics of Interest

Overview Titanium is an attractive structural material due to its high strength, low density, and excellent corrosion resistance. However, even though titanium is the fourth most abundant element in...

Magnesium anodizing can be used to improve the corrosion resistance, wear resistance, and hardness of the base magnesium metal. In addition, anodizing magnesium improves paint adhesion. This bulletin...

As the lightest structural metal available, magnesium's combination of low density and good mechanical strength results in a high strength-to-weight ratio. Because of their low modulus of elasticity,...

Overview While high strength steels normally account for only about 5 15% of the airframe structural weight, they are often used for highly critical parts such as landing gear components, control...

Automotive designers are specifying die-cast magnesium parts in applications once dominated by aluminum, zinc, and other structural materials. Production and New Program Manager, Magnesium and...