Mechanical Properties of Al-Mg Alloys at Elevated Temperatures / Mechanical Properties of Al-Mg Alloys at Elevated Temperatures

Comments on the Intermediate-Temperature Embrittlement of Metals and Alloys: The Conditions for Transgranular and Intergranular Failure

“…For these Al alloys, Hammad and Ramadan [51] found that increasing the strain rate in the range 5.5 × 10 −5 to 5.5 × 10 −3 s −1 decreased the hot ductility, as measured by elongation in an Al-3% Mg alloy. The alloy was solution treated and water quenched and tensile tested in the temperature range 27 to 530 • C. The high-temperature embrittlement was suggested as being due to precipitation of Al 3 Mg 2 and Mg 5 Al 3 compounds.…”

“…Creep normally manifests itself when the temperature (T) > 0.3-0.4 (T m ), where T m is the melting point in • C [91]. Hence for steel, copper, aluminium, and nickel, the ratios are 0.6, with the centre of the hot-ductility troughs being at ~900, 700, 250, and 400 • C, respectively, as noted in Table 2, with the data being taken from the literature [11,27,34,35,51,56,60]. Although Al alloys can have a hot-ductility trough in the intermediate-temperature region, it is most likely that when failure occurs on tensile testing these alloys in the temperature range of the trough, it is due to one of the following: the weakening of the cohesive strength of the boundaries, the formation of liquid films, or oxygen infiltration to the grain surfaces, rather than creep cavitation.…”

“…In the case of the segregation, it has relevant importance to the hot ductility due to its effect on the cohesive strength of grain boundaries. It is often suggested that the segregation of atoms to the grain boundaries at room temperature dictates the properties of metals such as strength, ductility and impact behaviour, corrosion, and weldability, particularly so for steel [50,51,55,87]. There is also a movement to use segregation to the boundaries as a means of designing alloys (DEA).…”