The genearlized planar fault energies of Al and Al-RE （RE = Sc, Y, Dy, Tb, Nd） alloys have been investigated using first-principles methods combined with a quasiharmonic approach. The stacking fault energies, unstab...The genearlized planar fault energies of Al and Al-RE （RE = Sc, Y, Dy, Tb, Nd） alloys have been investigated using first-principles methods combined with a quasiharmonic approach. The stacking fault energies, unstable stacking fault energies, and unstable twinning energies decrease slightly with increasing temperature. The ductility parameter D, the relative barrier difference Sut, and the twinnability τa of Al and Al-RE alloys at different temperatures have been determined. It is found that the ductilities of Al and Al alloys are nearly the same and the ductilities increase slightly with increasing temperature. The RE alloying elements make twinning more likely and the twinnabilities of Al and Al alloys decrease with increasing temperature.展开更多
The ω phase is commonly observed in β-Ti alloys and plays a significant role on various properties ofβ-Ti alloys.Although many results about the role of ω phase on mechanical properties of β-Ti alloys have been d...The ω phase is commonly observed in β-Ti alloys and plays a significant role on various properties ofβ-Ti alloys.Although many results about the role of ω phase on mechanical properties of β-Ti alloys have been derived from theoretical and experimental studies,the role of ω phase on deformation mechanism hitherto remains elusive and deserves to be further studied.In this work,the role played by ω phase during the {112} <111>_(β) twining in Ti-Mo alloys were investigated by first-principles calculations at atomic scale.In the energy favorable interface of(112)_(β)(110)_(ω),we found that partial dislocations slipping on the successive(1010)_(ω)planes of ω phase can lead to the formation of {112} <111>_(β) twin nucleus.And the twin nucleus grows inwards ω grain interior through atomic shuffle.Thus,a new twinning mechanism of {112} <111>_(β) assisted by ω phase was proposed.Furthermore,our calculations indicated that the appearance of ITB(interfacial twin boundary) ω phase can improve the stability of the symmetrical{112} <111>_(β) twin boundary(TB),which can well explain the experimental phenomenon that the ITBω phase always accompanies the formation of {112} <111>_(β) twin.Finally,a probable microstructure evolution sequence was suggested,namely β matrix→β matrix+athermal ω phase→(112)[111]_(β) twin+ITB ω phase.Our calculations provide new insights on the role played byω phase during the twinning process of {112} <111>_(β),which can deepen the understanding on the deformation behaviors of β-Ti alloys.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11104361 and 11304403)the Fundamental Research Funds for the Central Universities,China(Grant No.CQDXWL2012015)
文摘The genearlized planar fault energies of Al and Al-RE （RE = Sc, Y, Dy, Tb, Nd） alloys have been investigated using first-principles methods combined with a quasiharmonic approach. The stacking fault energies, unstable stacking fault energies, and unstable twinning energies decrease slightly with increasing temperature. The ductility parameter D, the relative barrier difference Sut, and the twinnability τa of Al and Al-RE alloys at different temperatures have been determined. It is found that the ductilities of Al and Al alloys are nearly the same and the ductilities increase slightly with increasing temperature. The RE alloying elements make twinning more likely and the twinnabilities of Al and Al alloys decrease with increasing temperature.
基金supported by the National Key R&D Program of China(No.2016YFB0701302)the CAS Frontier Science Research Project(No.QYZDJ-SSW-JSC015,QYZDY-SSW-JSC027)+1 种基金supported by the SYNL Basic Frontier&Technological Innovation Research Project(No.L2019R10)the computational support from the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)under Grant No.U1501501。
文摘The ω phase is commonly observed in β-Ti alloys and plays a significant role on various properties ofβ-Ti alloys.Although many results about the role of ω phase on mechanical properties of β-Ti alloys have been derived from theoretical and experimental studies,the role of ω phase on deformation mechanism hitherto remains elusive and deserves to be further studied.In this work,the role played by ω phase during the {112} <111>_(β) twining in Ti-Mo alloys were investigated by first-principles calculations at atomic scale.In the energy favorable interface of(112)_(β)(110)_(ω),we found that partial dislocations slipping on the successive(1010)_(ω)planes of ω phase can lead to the formation of {112} <111>_(β) twin nucleus.And the twin nucleus grows inwards ω grain interior through atomic shuffle.Thus,a new twinning mechanism of {112} <111>_(β) assisted by ω phase was proposed.Furthermore,our calculations indicated that the appearance of ITB(interfacial twin boundary) ω phase can improve the stability of the symmetrical{112} <111>_(β) twin boundary(TB),which can well explain the experimental phenomenon that the ITBω phase always accompanies the formation of {112} <111>_(β) twin.Finally,a probable microstructure evolution sequence was suggested,namely β matrix→β matrix+athermal ω phase→(112)[111]_(β) twin+ITB ω phase.Our calculations provide new insights on the role played byω phase during the twinning process of {112} <111>_(β),which can deepen the understanding on the deformation behaviors of β-Ti alloys.
