You're not even close to science. That's why you haven't been able to identify any error in the Harrit et al. paper or substantiate your nutty ideas that red/gray multilayered chips of unreacted nanothermite are produced by welding and are sitting around in buildings.
Here's how nanothermite is produced:
A method for producing nanoscale, or ultra fine grain (UFG) aluminium powders, a key component of most nano-thermitic materials, is the dynamic gas-phase condensation method, pioneered by Wayne Danen and Steve Son at Los Alamos National Laboratory. A variant of the method is being used at the Indian Head Division of the Naval Surface Warfare Center. Another production method for nanoaluminium powder is the pulsed plasma process developed by NovaCentrix (formerly Nanotechnologies).[9] The powders made by both processes are indistinguishable.[10] A critical aspect of the production is the ability to produce particles of sizes in the tens of nanometer range, as well as with a limited distribution of particle sizes. In 2002, the production of nano-sized aluminium particles required considerable effort, and commercial sources for the material were limited.[3] Current production levels are now beyond 100 kg/month.
An application of the sol-gel method, developed by Randall Simpson, Alexander Gash and others at the Lawrence Livermore National Laboratory, can be used to make the actual mixtures of nanostructured composite energetic materials. Depending on the process, MICs of different density can be produced. Highly porous and uniform products can be achieved by supercritical extraction.[3]
https://en.wikipedia.org/wiki/Nano-thermite
Notice that it doesn’t say anything about just doing some welding and you get red/gray multilayered chips.