TY - JOUR
T1 - Effects of Ti addition on the microstructure and mechanical properties of Al–Zn–Mg–Cu–Zr alloy
AU - Lee, Sang Hwa
AU - Jung, Jae Gil
AU - Baik, Sung Il
AU - Park, Sung Hyuk
AU - Kim, Min Seok
AU - Lee, Young Kook
AU - Euh, Kwangjun
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2021/1/13
Y1 - 2021/1/13
N2 - The effects of Ti addition (0.1 wt%) on the microstructure evolution and mechanical properties of an Al–7.6Zn–2.6Mg–2.0Cu–0.1Zr alloy were investigated during solidification, extrusion, solution treatment, and aging. The addition of Ti reduces the grain size and degree of phase agglomeration during solidification, thereby improving the strength and ductility of the as-cast alloy. The extrusion forms a bimodal structure consisting of fine dynamically recrystallized (DRXed) grains and coarse elongated unDRXed grains. Ti induces the refinement of the η-phases that enhances dynamic recrystallization (DRX) by particle-stimulated nucleation, resulting in reduced strength of the as-extruded alloy. The dissolution of the η-phase occurs in the initial stages of the solution treatment, followed by coarsening of the η-phase. The solution treatment causes static recrystallization and grain growth, increasing the grain size. The addition of Ti decreases the size and increases the number density of the L12 precipitate by modifying the chemical composition of (Al,Zn)3Zr into (Al,Zn)3(Zr,Ti), and causes the formation of an Al18Mg3Ti2 phase during the solution treatment. The addition of Ti also enhances heterogeneous nucleation of η-Mg(Zn,Cu,Al)2 at the Al18Mg3Ti2 interface and grain boundary but has a negligible effect on the formation of nanoprecipitates (GPII zone, η') in the matrix. The improved strength and ductility of the solution-treated and aged alloys are attributed to the higher number density of the fine L12-(Al,Zn)3(Zr,Ti) precipitates and grain refinement, as well as the finer η-phases acting as cracking sites.
AB - The effects of Ti addition (0.1 wt%) on the microstructure evolution and mechanical properties of an Al–7.6Zn–2.6Mg–2.0Cu–0.1Zr alloy were investigated during solidification, extrusion, solution treatment, and aging. The addition of Ti reduces the grain size and degree of phase agglomeration during solidification, thereby improving the strength and ductility of the as-cast alloy. The extrusion forms a bimodal structure consisting of fine dynamically recrystallized (DRXed) grains and coarse elongated unDRXed grains. Ti induces the refinement of the η-phases that enhances dynamic recrystallization (DRX) by particle-stimulated nucleation, resulting in reduced strength of the as-extruded alloy. The dissolution of the η-phase occurs in the initial stages of the solution treatment, followed by coarsening of the η-phase. The solution treatment causes static recrystallization and grain growth, increasing the grain size. The addition of Ti decreases the size and increases the number density of the L12 precipitate by modifying the chemical composition of (Al,Zn)3Zr into (Al,Zn)3(Zr,Ti), and causes the formation of an Al18Mg3Ti2 phase during the solution treatment. The addition of Ti also enhances heterogeneous nucleation of η-Mg(Zn,Cu,Al)2 at the Al18Mg3Ti2 interface and grain boundary but has a negligible effect on the formation of nanoprecipitates (GPII zone, η') in the matrix. The improved strength and ductility of the solution-treated and aged alloys are attributed to the higher number density of the fine L12-(Al,Zn)3(Zr,Ti) precipitates and grain refinement, as well as the finer η-phases acting as cracking sites.
KW - Aluminum alloys
KW - Atom probe tomography
KW - Electron microscopy
KW - Mechanical properties
KW - Precipitation
UR - http://www.scopus.com/inward/record.url?scp=85094185321&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2020.140437
DO - 10.1016/j.msea.2020.140437
M3 - Article
AN - SCOPUS:85094185321
SN - 0921-5093
VL - 801
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
M1 - 140437
ER -