Tesla has invented new aluminum alloys that can maintain high-yield strength and high conductivity while still being used for die casting electric car parts, according to a new patent filing.

We previously reported that Tesla and SpaceX are partnering up to create new materials to use on Earth and in space.

They have been building material engineering teams to develop new advanced materials for their respective products.

It started in 2016, when we reported in an exclusive story that Elon Musk hired Apple’s alloy expert Charles Kuehmann to lead materials engineering at both of his companies simultaneously.

Now we learn of new materials developed by the Tesla materials team led by Kuehmann: new aluminum alloys for die casting.

A new Tesla patent application reveals the new alloys.

In the patent application, Tesla describes the problems with the current aluminum alloys that they are trying to solve:

Commercial cast aluminum alloys fall into one of two categories — either possessing high-yield strength or possessing high conductivity. For example, the A356 aluminum alloy has a yield strength of greater than 175 MPa, but has a conductivity of approximately 40% IACS. Conversely, the 100.1 aluminum alloy has a conductivity of greater than 48% IACS, but a yield strength of less than 50MPa. For certain applications, for example, parts within an electric vehicle like a rotor or an inverter, both high strength and conductivity are desired. Further, because it is desired to form these electric-vehicle parts through a casting process, wrought alloys cannot be used. Rather, it is desirable to form the parts through a casting process, such that the parts may be cast quickly and reliably, such as through a low pressure and high velocity metal injection or a high pressure die casting process. After casting, suitable alloys must maintain their properties sufficiently for the necessary application. Poor castability of the alloy often results in observed hot tearing, and can cause fill issues which typically decreases the mechanical and electrical properties of the end cast part.

Therefore, Tesla is trying to create alloys with high-yield strength and conductivity while being resistant to hot tearing in order to be used in die casting drive unit components.

In comparison with the numbers listed above, Tesla claims that its new aluminum alloys can be tweaked to achieve yield strength of 90 MPa to 150 MPa and electrical conductivity of 40% IACS up to 60% IACS.

They also claim that the new alloys can support die casting:

In one embodiment, the alloy has the proper fluidity to ensure that the alloy wets the entire length of a mold and the mold is properly formed, and such that the alloy resists hot-tearing and retains the desired yield strength when the cast solidifies.

Here they released a bunch of test results:

For the material experts out there who want to know how Tesla achieves those results with its new alloys, here’s the full patent application:

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