The (100) texture of solidified fcc metals, caused by the preferential (100) dendrite growth, could be closeIy related to solid/melt interfaces which behave differently along different crystallographic orientation. Th...The (100) texture of solidified fcc metals, caused by the preferential (100) dendrite growth, could be closeIy related to solid/melt interfaces which behave differently along different crystallographic orientation. The stability and roughness of {111} and {100} solid/melt interfaces of fcc metals were investigated using a modified Temkin multi-layer model. It is demonstrated that {100}crystal/melt interface is more unstable and rougher than {111} interface. The effect of the stability of crystal/melt interface on the (100) texture formation in solidified fcc metals has been analysed and discussed.展开更多
In the present work the research of grain boundary (CB) energy versus angle of misorientation in fcc metals Al, Cu, An and Ni was carried out. An axis of CB misorientation is a direction [100], angle of misorientatio...In the present work the research of grain boundary (CB) energy versus angle of misorientation in fcc metals Al, Cu, An and Ni was carried out. An axis of CB misorientation is a direction [100], angle of misorientation makes from 2皍p in 23*. The interatomic interaction was opproximated by Morse' s pair semi-empirical potential. Two variants of relaxation technique were used: (1) rigid relax- ation with the change of atom quantity per a GB (vacancy relaxation ) and (2) full atomic relaxation by a molecular static method. The obtained orientation dependence has a good agreement with experi- ment. There are cusps on a curve in the range of special GB angles.The comparison of obtained curves with calculated ones in model Van der Merwe was carried out. Dependencies obtained in our investiga- tions are not smooth and have an oscillatory character. The oscillations reflect a discrete structure of a lattice.展开更多
Inherent twinnability of face-centered-cubic（fcc） metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation,with which the twinna...Inherent twinnability of face-centered-cubic（fcc） metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation,with which the twinnability of fcc metals can be simply expressed as function of the stacking-fault energy,the unstable stacking-fault energy,and the unstable twinningfault energy of fcc metals.The predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters.展开更多
In the present research, a simple quasi-continuum model, the Cauchy-Born rule model, is used to investigate the size effects of elastic modulus for fcc metals. By considering a nanoplate model and calculating the stra...In the present research, a simple quasi-continuum model, the Cauchy-Born rule model, is used to investigate the size effects of elastic modulus for fcc metals. By considering a nanoplate model and calculating the strain energy for the nano-sized plate under tension and bending, the relationship between the elastic modulus and the plate thickness is found. Size effects of the elastic modulus are displayed by the relative differences of the elastic modulus between the nano-sized plate sample and the bulk sample. By comparing the present results with those of others, the effectiveness of the Cauchy-Born rule model in studying the size effects of material properties are shown.展开更多
A rate-independent polycrystalline plasticity constitutive model considering self and latent hardening was developed. Next, a new orientation probability assignment method was proposed and the crystal orientations wer...A rate-independent polycrystalline plasticity constitutive model considering self and latent hardening was developed. Next, a new orientation probability assignment method was proposed and the crystal orientations were assigned to FE integration points, which represent crystals and can rotate individually. Then cup drawing of FCC aluminum sheet was studied using crystalline plasticity finite element analysis. The results show that the validity of proposed model is proved through comparison between numerical results and experimental ones. {001}<110> texture can lead to earing at 45° direction, while {124}<211> texture at 0° and 90° directions. For the rolled aluminum sheet, which contains strong {001}<110> texture, earing is formed at 45° direction after cup drawing. For the annealing aluminum sheet, due to the balance between two main textures, the flange earing tendency is not obvious.展开更多
文摘The (100) texture of solidified fcc metals, caused by the preferential (100) dendrite growth, could be closeIy related to solid/melt interfaces which behave differently along different crystallographic orientation. The stability and roughness of {111} and {100} solid/melt interfaces of fcc metals were investigated using a modified Temkin multi-layer model. It is demonstrated that {100}crystal/melt interface is more unstable and rougher than {111} interface. The effect of the stability of crystal/melt interface on the (100) texture formation in solidified fcc metals has been analysed and discussed.
文摘In the present work the research of grain boundary (CB) energy versus angle of misorientation in fcc metals Al, Cu, An and Ni was carried out. An axis of CB misorientation is a direction [100], angle of misorientation makes from 2皍p in 23*. The interatomic interaction was opproximated by Morse' s pair semi-empirical potential. Two variants of relaxation technique were used: (1) rigid relax- ation with the change of atom quantity per a GB (vacancy relaxation ) and (2) full atomic relaxation by a molecular static method. The obtained orientation dependence has a good agreement with experi- ment. There are cusps on a curve in the range of special GB angles.The comparison of obtained curves with calculated ones in model Van der Merwe was carried out. Dependencies obtained in our investiga- tions are not smooth and have an oscillatory character. The oscillations reflect a discrete structure of a lattice.
基金support from the "Hundred Talents Project" of CAS,the Cheung Kong Scholars Programthe National Natural Science Foundation of China (NSFC Grant No.10776032)+1 种基金Chinese MOST (Grant No. 2009CB623702)NSF (CMMI 0928517) through University of Pittsburgh
文摘Inherent twinnability of face-centered-cubic（fcc） metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation,with which the twinnability of fcc metals can be simply expressed as function of the stacking-fault energy,the unstable stacking-fault energy,and the unstable twinningfault energy of fcc metals.The predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters.
基金Project supported by the National Natural Science Foundation of China(Nos.11021262,10932011 and 91216108)the National Basic Research Program of China(2012CB937500)
文摘In the present research, a simple quasi-continuum model, the Cauchy-Born rule model, is used to investigate the size effects of elastic modulus for fcc metals. By considering a nanoplate model and calculating the strain energy for the nano-sized plate under tension and bending, the relationship between the elastic modulus and the plate thickness is found. Size effects of the elastic modulus are displayed by the relative differences of the elastic modulus between the nano-sized plate sample and the bulk sample. By comparing the present results with those of others, the effectiveness of the Cauchy-Born rule model in studying the size effects of material properties are shown.
文摘A rate-independent polycrystalline plasticity constitutive model considering self and latent hardening was developed. Next, a new orientation probability assignment method was proposed and the crystal orientations were assigned to FE integration points, which represent crystals and can rotate individually. Then cup drawing of FCC aluminum sheet was studied using crystalline plasticity finite element analysis. The results show that the validity of proposed model is proved through comparison between numerical results and experimental ones. {001}<110> texture can lead to earing at 45° direction, while {124}<211> texture at 0° and 90° directions. For the rolled aluminum sheet, which contains strong {001}<110> texture, earing is formed at 45° direction after cup drawing. For the annealing aluminum sheet, due to the balance between two main textures, the flange earing tendency is not obvious.
