This study reports that metals can become stronger when heated at extremely high strain rates, contrary to the usual behavior where heating typically softens materials. Using microballistic impact testing at strain rates exceeding 10⁶ s⁻¹, researchers observed that copper, titanium, and gold showed increased strength with temperature, an effect not seen under normal conditions. This anomalous thermal strengthening is attributed to a shift in deformation mechanism from thermally activated processes to ballistic dislocation transport, where dislocations experience drag through phonon interactions. The results suggest a new pathway for modeling and predicting material behavior under extreme strain rates, relevant for applications such as high-speed manufacturing and hypersonic transport. The study highlights that at high strain rates, the deformation mechanisms in metals change, leading to increased strength with temperature. This is due to the dominance of drag mechanisms over thermally activated ones, where dislocations interact with phonons, increasing their drag. The findings challenge previous assumptions about material behavior at high temperatures and emphasize the importance of understanding these mechanisms for designing materials for extreme conditions. The research used laser-induced particle impact tests to measure the strength and hardness of materials at extreme strain rates. The results show that the dynamic yield strength and hardness of copper increase with temperature, indicating thermal hardening. This effect is consistent across pure metals, suggesting a general trend in deformation mechanisms under extreme conditions. The study also provides insights into the transition between different deformation mechanisms and the role of temperature in controlling material behavior at high strain rates. The findings have implications for materials design and engineering, as they suggest that conventional strength measurements may not accurately predict material behavior under extreme conditions.This study reports that metals can become stronger when heated at extremely high strain rates, contrary to the usual behavior where heating typically softens materials. Using microballistic impact testing at strain rates exceeding 10⁶ s⁻¹, researchers observed that copper, titanium, and gold showed increased strength with temperature, an effect not seen under normal conditions. This anomalous thermal strengthening is attributed to a shift in deformation mechanism from thermally activated processes to ballistic dislocation transport, where dislocations experience drag through phonon interactions. The results suggest a new pathway for modeling and predicting material behavior under extreme strain rates, relevant for applications such as high-speed manufacturing and hypersonic transport. The study highlights that at high strain rates, the deformation mechanisms in metals change, leading to increased strength with temperature. This is due to the dominance of drag mechanisms over thermally activated ones, where dislocations interact with phonons, increasing their drag. The findings challenge previous assumptions about material behavior at high temperatures and emphasize the importance of understanding these mechanisms for designing materials for extreme conditions. The research used laser-induced particle impact tests to measure the strength and hardness of materials at extreme strain rates. The results show that the dynamic yield strength and hardness of copper increase with temperature, indicating thermal hardening. This effect is consistent across pure metals, suggesting a general trend in deformation mechanisms under extreme conditions. The study also provides insights into the transition between different deformation mechanisms and the role of temperature in controlling material behavior at high strain rates. The findings have implications for materials design and engineering, as they suggest that conventional strength measurements may not accurately predict material behavior under extreme conditions.