The core of this micolattice is from tungsten.

Here is some more info about the metal tungsten from wikipedia:

Tungsten, also known as wolfram, is a chemical element with symbol W and atomic number 74. The word tungsten comes from the Swedish languagetung sten, which directly translates to heavy stone.^[4] Its name in Swedish is volfram, however, in order to distinguish it from scheelite, which in Swedish is alternatively named tungsten.

A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783.

We’re looking forward to seeing the microlattice metal in new applications.

thanks to Boeing for the great info