Scientists have identified a previously unknown metal alloy believed to have formed during the atomic bomb explosion over Hiroshima in Japan in 1945.
The microscopic alloy was discovered inside tiny grains of radioactive fallout, known as “hiroshimaite,” collected from beach sands in Hiroshima Bay nearly 80 years after the bombing.
Researchers believe the alloy was created inside the nuclear fireball, where temperatures exceeded 7,000 degrees Celsius. Under those extreme conditions, buildings, steel, glass and soil were instantly vaporised before rapidly cooling, producing a material unlike any previously documented.
The newly identified alloy is composed of iron, chromium, nickel, manganese, molybdenum, silicon and aluminium—elements commonly found in stainless steel. However, scientists found that the atoms combined into a completely new crystal structure as the molten material cooled at an exceptionally rapid rate.
The discovery was made by researchers from the University of Florence while examining 34 glass-like fallout particles recovered from Hiroshima Bay. Using advanced microscopy and X-ray analysis, the team searched for unusual materials created during the explosion.
One metallic grain, measuring only a few thousandths of a millimetre, attracted the researchers’ attention because its atomic structure did not match any known material. After comparing it with thousands of existing alloys, the scientists concluded that they had identified a previously unknown multicomponent alloy.
In a study published in the journal Science Advances, the researchers wrote: “We report the discovery of a previously unknown multicomponent alloy recovered from beach sands of Hiroshima Bay, formed during the August 6, 1945 atomic airburst.”
The researchers said the discovery suggests that other previously unknown materials may still exist within microscopic debris left behind by the Hiroshima bombing. They added that studying such materials could improve scientific understanding of how matter behaves under extreme temperatures and pressures.
The atomic bomb, codenamed Little Boy, was dropped on Hiroshima at 8:15 a.m. on August 6, 1945. It detonated about 1,900 feet above the city with an explosive force equivalent to approximately 15,000 tons of TNT.
Historical records estimate that between 60,000 and 80,000 people were killed immediately by the blast, while the death toll rose to about 140,000 by the end of 1945 as many others succumbed to burns, injuries and radiation-related illnesses.