Influence of Overaging on the Superplastic Behavior of an Al-Zn-Mg-Cu-Zr-Sc Alloy

Abstract

This study examines the influence of overaging on the superplastic behavior of an Al-8.55Zn-2.65Mg-2.48Cu-0.1Zr-0.06Sc alloy (in mass%). Results show that the M-phase particles formed during overaging play the most crucial role during the high-temperature tensile deformation of the Al-Zn-Mg-Cu-Zr-Sc alloy. Even though specimens without overaging maintain their small grain structure due to the existence of fine coherent Al 3 (Sc x Zr 1Àx ) particles, overaged specimens exhibit better superplasticity. The presence of liquid-like viscous flow may be the main factor contributing to the superior superplasticity of overaged specimens.

Investigation of Microstructure And Mechanical Properties of Al-Zn-Mg and Al-Zn-Mg-Sc Alloys After Double Passes Friction Stir Processing

“…Moreover, solution treatment at 465 o C for 1h then immediately water quenching (T4) reduces the cast inhomogeneity, grain boundary segregation and dissolve inclusions like η (MgZn2) and Τ(Al2Zn3Mg3) phases in the temperature range 435-445 o C in the matrix [7]. Loss of thermal conductivity is significantly degraded by multiply alloying precipitation hardening elements such as Mg, Fe, and Si [8], [9]. FSP is the advanced solid state technique to modify cast surface layers and to enhance specific properties to some considerable depth.…”