| Titanium alloys are widely used in many fields such as aerospace and automobile production due to their high strength and low density.α-titanium alloy has poor plastic coordination ability and many factors affect its deformation mechanism due to the HCP structure at room temperature.Therefore,exploring the plastic deformation behavior and deformation mechanism under various conditions can provide theoretical guidance for the use of materials in different environments.As a very common alloying element in titanium alloy,aluminum(Al)has an important effect on the deformation mechanism of materials.Based on this,Ti-10at.%Al alloy was studied in this article to explore the influence of strain rate and temperature on deformation mechanism.In addition,the effect of loading along different directions on the deformation mechanism was also studied because obvious texture existed in the pre-treated sample.At the same time,the hardness of materials under various deformation conditions was characterized,and the relationship between microstructure and mechanical properties was revealed.The research contents and main conclusions are as follows:(1)Ti-10at.%Al alloy was deformed by high speed compression and quasi-static compression under different strains along normal direction(ND)respectively,and various deformation mechanisms during the deformation process were explored.With the increase of strain,the number of twins increased first and then basically remained constant,and the {11(?)2} twinning was inhibited obviously.In addition,adiabatic shear bands were observed.In quasi-static compression,the number of twins was significantly reduced compared with high speed compression.Dislocation planar slip was observed in Ti-10at.%Al alloy,while dislocation cross slip occurred in pure Ti during deformation,which might be related to the reduction of stacking fault energy or the formation of short-range ordered structure caused by the addition of Al.In addition,the hardness changes were also explored to reveal the work hardening effect.(2)Ti-10at.%Al alloy was rolled at room temperature(298 K),low temperature(77 K)and high temperature(773 K)along normal direction(ND)to investigate the effect of temperature on deformation mechanism.Compared with rolling at room temperature,more twins were observed in rolling at low temperature,and {11(?)1} twinning was obviously inhibited during rolling at high temperature.When rolling at low temperature,dislocation slip was reduced and some thin laths appeared.Microbands appeared during rolling at room temperature.Recovery occurred during high temperature rolling and the dislocation density per unit area was reduced.During rolling at room and low temperature,dislocation planar slip was observed,while the cross slip occurred during rolling at high temperature,which is mainly due to the temperature change of the laminated fault energy in the material,which is mainly due to the change of the stacking fault energy in the material by temperature.(3)Ti-10at.%Al alloy was deformed along the transverse direction(TD)under high speed compression and rolling at different temperatures,and compared with the results of(1)and(2).The effect of loading direction on deformation mechanism was investigated.It is found that the number of twins in the TD direction is higher than that in the ND direction.This is mainly because the deformation along the TD direction is more favorable to the growth of {11(?)1} twinning,while the ND direction is more dependent on<c+a>dislocation to coordinate deformation.Loading in both directions weakens the original texture.At the local area of high speed compression,twinning induced twinning at grain boundary occurs,which is mainly affected by twinning matching factor.In addition,it is found that the lower the deformation temperature,the better the hardening effect.The hardness values along ND direction are generally higher than those along TD direction.44 figures,4 tables,7 equations and 107 piece of references... |
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