Strain behavior and acoustic emission in aluminummagnesium alloy under non-isothermal termomechanical loading are investigated. The strain accumulation in the alloy within the temperature range from room temperature to 500 °C proceeds in two temperature intervals (I, II) with different straining rates. The rate of strain accumulation is correlated with acoustic emission. When the loading in cycles increases from 40 MPa to 200 MPa, changes of the boundary temperature (T_GR) between intervals I and II are non-monotone. For the cycles with loading up to 90 MPa the T_GR values increase, while further for the cycles with loading up to 200 MPa the T_GR values shift into the low-temperature area. This fact demonstrates that shifting of the boundary into the lowtemperature area and appearance of high-amplitude pulses of acoustic emission describes the reduction of thermal fluctuation when mechanical loading increases causing interatomic bond breakups during elementary deformation.