The solid-liquid interracial morphology evolution was investigated in directional solidification （DS） of Al-1.5%Cu alloy （mass fraction）. The results show that the solidified microstructural evolution is gradual o...The solid-liquid interracial morphology evolution was investigated in directional solidification （DS） of Al-1.5%Cu alloy （mass fraction）. The results show that the solidified microstructural evolution is gradual other than sharp, and the microstructure patterns are interesting and diversiform at the pulling rate ranging from 30 μm/s to 1500 μm/s. Indeed, dendrite to cell transition follows this sequence： dendrites→→banded cellular dendrites→elongated cells and part of dendrites→main elongated cells and little dendrites. Moreover, the present microstructure is not normal microstructure as we saw before. Further, according to the experimental phenomenon, the dendrite to cell transition was studied theoretically. Dendrite tip shape is an important parameter to characterize the dendrite to cell transition. As the dendrite to cell transition is far from equilibrium solidification, non-equilibrium solidification is taken into consideration in calculation. Finally, it is speculated that the dendrite to cell transition would occur at the minimum tip radius.展开更多
Evaluation of adhesion of PVD Ti and TiN films on steel A_3 was carried out with constant rate pulling test(CRPT)at 0.05 mm/min under simultaneous SEM observation. As a criterion,the critical elongations of the film/s...Evaluation of adhesion of PVD Ti and TiN films on steel A_3 was carried out with constant rate pulling test(CRPT)at 0.05 mm/min under simultaneous SEM observation. As a criterion,the critical elongations of the film/substrate system for the initial cracking and spelling of the film may be applied to evaluate the plasticity and adhesion of the film to substrate.The conventional scratch test was also made for evaluation of the adhesion for the same systems.Both methods give the coordinate assessment for all the systems. In addition,the influence of the films on the ultimate yield strength of the substrate was discussed and another criterion of conherent work was proposed for the evaluation.展开更多
基金Project(SKLSP201418)supported by the Fund of the State Key Laboratory of Solidification Processing in North China University of Technology,ChinaProjects(51171151,51331005)supported by the National Natural Science Foundation of China
文摘The solid-liquid interracial morphology evolution was investigated in directional solidification （DS） of Al-1.5%Cu alloy （mass fraction）. The results show that the solidified microstructural evolution is gradual other than sharp, and the microstructure patterns are interesting and diversiform at the pulling rate ranging from 30 μm/s to 1500 μm/s. Indeed, dendrite to cell transition follows this sequence： dendrites→→banded cellular dendrites→elongated cells and part of dendrites→main elongated cells and little dendrites. Moreover, the present microstructure is not normal microstructure as we saw before. Further, according to the experimental phenomenon, the dendrite to cell transition was studied theoretically. Dendrite tip shape is an important parameter to characterize the dendrite to cell transition. As the dendrite to cell transition is far from equilibrium solidification, non-equilibrium solidification is taken into consideration in calculation. Finally, it is speculated that the dendrite to cell transition would occur at the minimum tip radius.
文摘Evaluation of adhesion of PVD Ti and TiN films on steel A_3 was carried out with constant rate pulling test(CRPT)at 0.05 mm/min under simultaneous SEM observation. As a criterion,the critical elongations of the film/substrate system for the initial cracking and spelling of the film may be applied to evaluate the plasticity and adhesion of the film to substrate.The conventional scratch test was also made for evaluation of the adhesion for the same systems.Both methods give the coordinate assessment for all the systems. In addition,the influence of the films on the ultimate yield strength of the substrate was discussed and another criterion of conherent work was proposed for the evaluation.
