摘要
通过对具有三级沉淀微观结构的CoCrNiSi_(0.3)C_(0.048)中熵合金(MEA)进行了Taylor冲击试验,形成了具有宽泛应变和应变率梯度的Taylor杆状试样,研究了其应变和应变率依赖的梯度微观结构分布特征及演化机制.随着应变和应变率的增加,一级Cr_(23)C_(6)碳化物的演变方式主要为裂纹数量增多,主裂纹中裂纹分叉增多以及裂纹宽度变大.二级Type-Ⅰ型SiC沉淀变形的演变方式主要为裂纹的产生和扩展.三级Type-Ⅱ型SiC沉淀主要为位错-绕过机制逐渐加剧.FCC基体的演变方式主要为位错与孪晶和三级沉淀之间的相互作用加剧.
The excellent mechanical and physical properties of interstitial medium/high-entropy alloys(M/HEAs)give them significant potential for development in major projects such as national defense,military,aerospace,and other fields.The strain-and strain-rate-dependent gradient microstructure distribution characteristics and evolution mechanism of CoCrNiSi_(0.3)C_(0.048)medium-entropy alloy(MEA)with threelevel precipitate microstructure were studied through high-speed impact tests.The three-level precipitate microstructure is mainly composed of the primary Cr_(23)C_(6)carbides(2~10μm),the secondary SiC precipitates(200~500nm)around the grain boundaries,and the tertiary SiC precipitates(~50nm)within the grains.First,the Taylor impact tests were carried out on CoCrNiSi_(0.3)C_(0.048)MEA,resulting in a wide range of strain and strain rate gradient distribution in Taylor specimens.The microstructure characterization of different areas of the Taylor specimens,from near the impact end to the free end under different impact velocities,was examined and analyzed according to the three phases of Taylor impact test process:1)the stage of nonlinear motion of the plastic wavefront;2)the stage of steady motion of the plastic wavefront;and 3)the stage in which the velocity of the plastic wavefront reaches zero.It was found that with the increase of strain and strain rate,the primary Cr_(23)C_(6)carbides underwent an evolution process involving the increase of cracks,crack branching,and crack widening.For the secondary Type-I SiC precipitates,the evolution process primarily involved the formation and propagation of cracks.However,the tertiary Type-II SiC precipitates mainly exhibited a gradual intensification of the dislocation-bypass mechanism.In the FCC matrix,the interaction between dislocations,twins,and the three-level hierarchical precipitates became intensified with the increase of strain and strain rate.The present work not only reveals the strain-and strain-rate-dependent evolution mechanisms of interstitial MEAs but also pro
作者
王强
张团卫
王建军
赵聃
焦志明
马胜国
吴桂英
王志华
Qiang Wang;Tuanwei Zhang;Jianjun Wang;Dan Zhao;Zhiming Jiao;Shengguo Ma;Guiying Wu;Zhihua Wang(Institute of Applied Mechanics,College of Mechanical and Vehicle Engineering,Taiyuan University of Technology,Taiyuan,030024;Shanxi Key Laboratory of Material Strength and Structural Impact,Taiyuan University of Technology,Taiyuan,030024)
出处
《固体力学学报》
CAS
CSCD
北大核心
2023年第6期755-770,共16页
Chinese Journal of Solid Mechanics
基金
国家杰出青年科学基金(12225207)
国家自然科学基金(12072220,12102291)
山西省基础研究计划(20210302124386)
山西省科技创新人才领军团队项目(202204051002006)资助
关键词
Taylor冲击试验
宽泛应变和应变率
微观演化机制
间隙中熵合金
层级沉淀
Taylor impact test
a wide range of strains and strain rates
microstructure evolution mechanism
interstitial medium-entropy alloys
hierarchical precipitates
