TY - JOUR
T1 - Effect of vanadium micro-alloying on the microstructural evolution and creep behavior of Al-Er-Sc-Zr-Si alloys
AU - Erdeniz, Dinc
AU - Nasim, Wahaz
AU - Malik, Jahanzaib
AU - Yost, Aaron R.
AU - Park, Sally
AU - De Luca, Anthony
AU - Vo, Nhon Q.
AU - Karaman, Ibrahim
AU - Mansoor, Bilal
AU - Seidman, David N.
AU - Dunand, David C.
N1 - Funding Information:
This publication was made possible by a National Priorities Research Program grant from the Qatar National Research Fund ( NPRP 7-756-2-284 ) (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors. The authors thank Prof. Georges Ayoub (University of Michigan-Dearborn) and Dr. Keith Knipling (Naval Research Labs, Washington, DC, USA) for useful discussions. APT was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomography system was purchased and upgraded with funding from NSF-MRI ( DMR-0420532 ) and ONR-DURIP ( N00014-0400798 , N00014-0610539 and N00014-0910781 ) grants. The authors also gratefully acknowledge the Initiative for Sustainability and Energy at Northwestern (ISEN) for grants to upgrade the capabilities of NUCAPT. They thank Drs. Dieter Isheim and Sung-Il Baik (Northwestern University, Evanston, IL, USA) for their assistance with APT. This work made use of the OMM Facility which receives support from the MRSEC Program ( NSF DMR-1121262 ) of the Materials Research Center at Northwestern University. Transmission Electron Microscopy imaging was done in Microscopy and Imaging Center (MIC) at Texas A&M University and analysis is credited to Dr. Ruben Santamarta (Universitat de les Illes Balears, Spain). DNS and DCD have financial interests in NanoAl, LLC, which could potentially benefit from the outcomes of this research upon its publication.
Publisher Copyright:
© 2016 Acta Materialia Inc.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - Al-Er-Sc-Zr-Si alloys, strengthened by L12-ordered, coherent Al3(Er,Sc,Zr) nanoscale precipitates, can be used for automotive and aerospace applications up to 400 °C. Vanadium, due to its small diffusivity in aluminum and its ability to form L12-ordered tri-aluminide precipitates, is a possible micro-alloying addition for further improving the service temperature of these alloys. Moreover, vanadium-containing Al3(Er,Sc,Zr,V) precipitates are anticipated to have a smaller lattice parameter mismatch with the matrix, thereby improving the alloy's coarsening resistance. In this study, the temporal evolution of microstructural and mechanical properties of an Al-0.005Er-0.02Sc-0.07Zr-0.06Si alloy micro-alloyed with V are investigated utilizing isochronal, isothermal and double-aging treatments and compared to the results obtained from an alloy that does not contain V, but otherwise has the same composition. Both isochronal and isothermal aging treatments reveal slower precipitation and coarsening kinetics for the V-containing alloy. A peak microhardness value of ∼600 MPa is obtained after a double-aging treatment at 350 °C/16 h, followed by aging at 400 °C for 12 h. Transmission electron microscopy reveals a duplex-size precipitate microstructure, with the smaller precipitates having a mean radius <3 nm. Despite the expectation of a reduced creep resistance due to a lower precipitate/matrix lattice mismatch, both alloys have similar creep behavior at 400 °C, characterized by a threshold stress of 7.5 and 8 MPa under peak-aged and over-aged conditions, respectively. Thus, micro-additions of V to an Al-Er-Sc-Zr-Si alloy lead to enrichment of V in the Al3(Er,Sc,Zr,V) nano-precipitates, improving their coarsening resistance without deteriorating their ability to block dislocations under creep at 400 °C.
AB - Al-Er-Sc-Zr-Si alloys, strengthened by L12-ordered, coherent Al3(Er,Sc,Zr) nanoscale precipitates, can be used for automotive and aerospace applications up to 400 °C. Vanadium, due to its small diffusivity in aluminum and its ability to form L12-ordered tri-aluminide precipitates, is a possible micro-alloying addition for further improving the service temperature of these alloys. Moreover, vanadium-containing Al3(Er,Sc,Zr,V) precipitates are anticipated to have a smaller lattice parameter mismatch with the matrix, thereby improving the alloy's coarsening resistance. In this study, the temporal evolution of microstructural and mechanical properties of an Al-0.005Er-0.02Sc-0.07Zr-0.06Si alloy micro-alloyed with V are investigated utilizing isochronal, isothermal and double-aging treatments and compared to the results obtained from an alloy that does not contain V, but otherwise has the same composition. Both isochronal and isothermal aging treatments reveal slower precipitation and coarsening kinetics for the V-containing alloy. A peak microhardness value of ∼600 MPa is obtained after a double-aging treatment at 350 °C/16 h, followed by aging at 400 °C for 12 h. Transmission electron microscopy reveals a duplex-size precipitate microstructure, with the smaller precipitates having a mean radius <3 nm. Despite the expectation of a reduced creep resistance due to a lower precipitate/matrix lattice mismatch, both alloys have similar creep behavior at 400 °C, characterized by a threshold stress of 7.5 and 8 MPa under peak-aged and over-aged conditions, respectively. Thus, micro-additions of V to an Al-Er-Sc-Zr-Si alloy lead to enrichment of V in the Al3(Er,Sc,Zr,V) nano-precipitates, improving their coarsening resistance without deteriorating their ability to block dislocations under creep at 400 °C.
KW - Aluminum alloys
KW - Atom-probe tomography
KW - High temperature creep
KW - Microstructure
KW - Precipitation strengthening
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U2 - 10.1016/j.actamat.2016.11.033
DO - 10.1016/j.actamat.2016.11.033
M3 - Article
AN - SCOPUS:84996917606
SN - 1359-6454
VL - 124
SP - 501
EP - 512
JO - Acta Materialia
JF - Acta Materialia
ER -