Next-Gen Laptop Materials: Aluminum Alloy vs. Magnesium Alloy vs. Carbon Fiber

We’re currently experiencing a renaissance of laptops, with both incredible specifications and some really amazing design work adorning the latest models. As part of these next-generation designs, we’re also seeing a lot of new materials going into laptops as well. Aluminum, magnesium, carbon fiber, even the super-tough tempered Gorilla Glass—it seems that if you want to make a new high-end laptop or tablet, old-fashioned plastic just isn’t an option anymore.

But what are the pros and cons of these new materials, and which one should get the edge if you’re choosing between models? Let’s take a look.

Aluminum Alloy

If there’s an “older” option with the new generation of laptop designs, it’s aluminum. Famously employed by Apple on its high-end PowerBooks way back in 2003, aluminum alloy replaced the titanium alloy of older generations. The reasoning was twofold: using the anodizing process to finish and color the metal solved the paint chipping issue of previous generations, and aluminum is cheaper to buy and work with than titanium. While its lower density means that aluminum shells need to be thicker, that extra stiffness generally results in a design that’s less prone to bending, warping, and denting.

It wasn’t until the introduction of the Macbook Air that Apple debuted its “unibody” design language, with┬áthe main body (and later the screen assembly) formed out of a single piece of machine-milled aluminum alloy. This is has now become more or less the standard for high-end laptops. While manufacturing these specific parts is expensive, it allows laptops to be designed with fewer body parts overall, simplifying manufacturing as a whole and making them less prone to body warping and deformation. Some laptops as cheap as $300 feature aluminum body designs, though without the milled single-piece body design. Anodizing, an alloy treatment that can help with heat dissipation and corrosion resistance, can also be used to “dye” aluminum different colors.

The ASUS Chromebook flip, with a full aluminum body, can be had for less than $300.

Aluminum alloys are typically stronger than plastics, especially when used in unibody designs. But they come with some fairly obvious downsides: even the relatively thick bodies of premium aluminum laptops will dent if impacted hard enough, and they’ll do so more frequently than plastics due to lack of flex in a multi-part chassis. Aluminum also conducts heat much better than plastic, making some laptops prone to uncomfortable overheating. Significant engineering needs to be employed at the design stage to keep hot zones like the processor and heatsinks away from areas where the user is likely to touch the machine for extended periods of time.

Magnesium Alloy

Magnesium, an alternative to aluminum, is used as a primary alloy for an increasing number of laptop designs. It’s lighter by volume than aluminum by approximately 30% (it’s actually the lightest structurally-used metal in the world), while having a greater strength-to-weight ratio. This allows magnesium alloy electronics bodies to be thinner than similar aluminum designs with the same general durability. Magnesium is also less thermally conductive, meaning designers have more freedom in placing internal components that won’t create an uncomfortably hot case.

Microsoft’s Surface series uses magnesium alloy bodies and frames.

Magnesium is generally easier to use than aluminum in terms of manufacturing, opening up new design capabilities for laptop and tablet makers. Unfortunately, it’s also considerably more expensive as a metal. To offset this, manufacturers will sometimes combine magnesium shells with cheaper plastic parts on the frame or internal areas like the palm rest. Full magnesium-bodied designs, like the Surface Pro and some premium entries in the HP ENVY and Lenovo ThinkPad lines, tend to be more expensive than comparable models.

Between aluminum alloy and magnesium alloy, there really isn’t enough of a difference to sway a new laptop purchase one way or the other. With increased rigidity a magnesium case might be less likely to bend or dent than an aluminum one, but it’s also more prone to crack with increased pressure. The thermal properties probably won’t be all that noticeable (since manufacturers have become quite good at managing internal heat anyway). Unless you plan to constantly use a laptop in high-temperature environments, the internal specifications should probably be a more pressing concern.

Carbon Fiber

Carbon fiber is a bit of a misnomer: the material that’s so popularly depicted on airplanes and sports cars is in fact a composite of both woven carbon strands and more rudimentary polymer bases. Basically, it’s a high-tech plastic reinforced with synthetic carbon. The result is a material with an extremely high weight-to-strength ratio, allowing for protection similar to a metal or alloy at a fraction of the weight.

Also, it looks really cool. Most manufacturers like to show off the carbon fiber material in their designs, resulting in a distinctive grey-and-black weave that’s instantly recognizable.

Dell’s XPS laptops use carbon fiber bodies with aluminum alloy lids and bottoms.

The material is, at least in some ways, easier to mold and shape than metal, requiring only a simple cast mold for larger pieces rather than a machine-controlled milling process. Carbon fiber conducts heat at a fraction of the rate of either aluminum or magnesium, making it an ideal choice for areas of the laptop case where users are likely to place skin, like the palm rest.

However, carbon fiber does have some distinct disadvantages over more conventional laptop materials. Because it is a composite of the carbon weave and more fragile polymer, its finish isn’t anywhere near as durable as the woven interior—it’s much more susceptible to visible scratches and dents. The components beneath might be nearly as safe as they are underneath metal, but a corner drop or piercing impact will still look pretty bad. Carbon fiber is also much more expensive to produce than even magnesium alloy.

The ThinkPad Carbon line uses carbon fiber frames and magnesium body panels.

Because of this, it’s being deployed primarily as a combination material, with cases using lightweight and attractive carbon fiber on interior components like the palmrest and touchpad while using alloy metal on the exterior. To my knowledge, there hasn’t been a laptop body made entirely out of carbon fiber (though there have been a few smartphones made from structurally similar Kevlar).

Tempered Glass

The rise of smartphones in the late 2000s made tempered glass—Corning’s patented Gorilla Glass in particular—a newly-considered structural material for all sorts of electronics. In addition to the fairly obvious use for touch screen laptops, some newer designs have used tempered glass for laptop lids and even premium, smooth-tracking touchpads.

Some HP Spectre laptops use tempered glass lids, screens, palmrests, and touchpads.

Modern tempered glass is some amazing stuff, incorporating scratch resistance that’s almost as good as materials like synthetic sapphire. It also feels pretty nice, and it’s now relatively inexpensive to integrate into a laptop’s design. Since manufacturers like ASUS already have huge orders for smartphone glass, why not stick a little on a laptop?

But be aware, tempered glass is still…well, glass. It might be scratch-resistant and less likely to break than a typical window pane, but a drop onto any reasonably hard surface will still shatter screens, lids, and touchpads. As a material for laptop and tablet bodies, tempered glass is a cosmetic addition, and not a particularly durable one.

Image sources: Dell, ASUS, Lenovo, HP

Michael Crider has been covering technology on the web since 2011. His interests include folk music, football, science fiction, and salsa verde, in no particular order. He wrote a novel called Good Intentions: A Supervillain Story, and it's available on Amazon. You can follow him on Twitter if you want.