HARDENING AND SOFTENING PROCESSES IN AN AJ51 MAGNESIUM ALLOY REINFORCED WITH SHORT SAFFIL FIBRES

摘要

AJ51 alloy (5Al-0.6Sr balance Mg in wt.%) reinforced with shortδ-Al_2O_3 fibres (Saffil®) has been deformed in compression attemperatures between 23 and 300 °C. The yield stress and themaximum stress decrease with increasing testing temperature. Theinfluence of reinforcement on both characteristic stresses fallsdown with increasing temperature. Various strengthening termswere taken into account. Individual strengthening terms werecalculated and compared with experimental results. Acousticemission signal recorded during plastic deformation of the matrixalloy and composite was used to elucidate details of the plasticdeformation in the matrix alloy and composite. Residual thermalstresses, generated due to a great difference between the thermalexpansion coefficients of the alloy and ceramic reinforcement, inthe composite matrix at different strain levels were estimatedusing neutron diffraction method.