Anomalies in the temperature dependences of the bulk and shear strength ofaluminum single crystals in the submicrosecond range

The results of measurements of the dynamic yield stress and the ultimate st rength of aluminum single crystals in the temperature range from 15 to 650 degreesC, which is only 10 degreesC lower than the melting point, are prese nted. The measurements are made on samples under the action of plane shock waves with a pressure up to 5 GPa behind the front and of a duration of sim ilar to 2 x 10(-7) s. It is found that the dynamic yield stress anomalously increases, attaining, in the vicinity of the melting point, a value four t imes as high as that measured at room temperature. The dynamic strength of the single crystals in this temperature range decreases approximately by 40 %, a high strength being preserved in the state in which melting during ext ension is expected. (C) 2001 MAIK "Nauka/Interperiodica".