TY - JOUR

T1 - Compressive creep behavior and microstructural evolution of sand-cast and peak-aged Mg–12Gd–0.4Zr alloy at 250 °C

AU - Shi, Hui

AU - Huang, Yuanding

AU - Yang, Lixiang

AU - Liu, Chunquan

AU - Dieringa, Hajo

AU - Lu, Chong

AU - Xiao, Lv

AU - Willumeit-Römer, Regine

AU - Hort, Norbert

N1 - Funding Information: This work was financially supported by the National Natural Science Foundation of China ( U2037601 ), Shanghai Sailing Program ( 23YF1417100 ), and China Scholarship Council (Grant No: 202006890008 ), China. Hui Shi would also like to acknowledge Dr. Chong Lu, Dr. Lixiang Yang and Dr. Chunquan Liu for TEM characterizations; Mr. Gert Wiese and Ms. Petra Fischer regarding characterizations using OM and SEM; Dr. Maria Serdechnova for XRD test in this study. Publisher Copyright: © 2023 Elsevier B.V.

PY - 2023/8/24

Y1 - 2023/8/24

N2 - Magnesium (Mg) alloys with high concentrations of Gd additions are known to exhibit high strength and good creep resistance at elevated temperatures. However, the main mechanisms including microstructural evolution and dislocation configurations for clarifying the low creep rates of Mg–Gd–Zr alloys are still controversial. The present work investigates the compressive creep behavior of both the sand-cast and peak-aged Mg–12Gd–0.4Zr (wt.%) alloys at a fixed temperature of 250 °C under the applied stress range of 60–100 and 80–120 MPa, respectively. It is revealed that β' and β'F precipitates distribute alternately forming precipitate chains in Mg–Gd–Zr alloys. Furthermore, β'+β'F precipitate chains led to the honeycomb-like structure in the sand-cast alloy during the creep process, improving its creep resistance to some extent. Nevertheless, weakly strengthening β1 precipitates occurred and detrimental β phases coarsened, which weakened the creep performance of the sand-cast alloy. However, the slight improvement of creep resistance in the peak-aged Mg–12Gd–0.4Zr alloy can be mainly attributed to the formation of precipitate-free zones (PFZs) and also the premature coarsening of β'+β'F precipitate chains. During creep, the cross slip of basal and prismatic dislocations become the dominant creep mechanism for the sand-cast alloys. By contrast, the cross-slip of basal dislocations and pyramidal dislocations is the dominant creep mechanism for the peak-aged alloys, which was arrested by precipitates then strengthening the creep resistance of peak-aged alloys.

AB - Magnesium (Mg) alloys with high concentrations of Gd additions are known to exhibit high strength and good creep resistance at elevated temperatures. However, the main mechanisms including microstructural evolution and dislocation configurations for clarifying the low creep rates of Mg–Gd–Zr alloys are still controversial. The present work investigates the compressive creep behavior of both the sand-cast and peak-aged Mg–12Gd–0.4Zr (wt.%) alloys at a fixed temperature of 250 °C under the applied stress range of 60–100 and 80–120 MPa, respectively. It is revealed that β' and β'F precipitates distribute alternately forming precipitate chains in Mg–Gd–Zr alloys. Furthermore, β'+β'F precipitate chains led to the honeycomb-like structure in the sand-cast alloy during the creep process, improving its creep resistance to some extent. Nevertheless, weakly strengthening β1 precipitates occurred and detrimental β phases coarsened, which weakened the creep performance of the sand-cast alloy. However, the slight improvement of creep resistance in the peak-aged Mg–12Gd–0.4Zr alloy can be mainly attributed to the formation of precipitate-free zones (PFZs) and also the premature coarsening of β'+β'F precipitate chains. During creep, the cross slip of basal and prismatic dislocations become the dominant creep mechanism for the sand-cast alloys. By contrast, the cross-slip of basal dislocations and pyramidal dislocations is the dominant creep mechanism for the peak-aged alloys, which was arrested by precipitates then strengthening the creep resistance of peak-aged alloys.

KW - Magnesium alloys

KW - Compressive creep

KW - Creep mechanism

KW - Precipitates

KW - Dislocation

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85165343047&partnerID=8YFLogxK

U2 - 10.1016/j.msea.2023.145422

DO - 10.1016/j.msea.2023.145422

M3 - Journal articles

VL - 882

JO - Materials Science & Engineering A

JF - Materials Science & Engineering A

SN - 0921-5093

M1 - 145422

ER -