Grain size and texture can be controlled to improve the strength and ductility of magnesium rare-earth(Mg-RE)alloys by alloying.Directed energy deposition-arc(DED-arc)is a typical sub-rapid solidification process that...Grain size and texture can be controlled to improve the strength and ductility of magnesium rare-earth(Mg-RE)alloys by alloying.Directed energy deposition-arc(DED-arc)is a typical sub-rapid solidification process that contributes to the modification of the microstructure.In this paper,a series of novel Mg-3.0Nd-0.2Zn-0.3Zr-xCe(NZ30K-xCe)alloys with different Ce contents(0,0.1,0.3,0.5 wt.%)were prepared by DED-arc.The results show that the experimental alloys have lower porosity(≤0.11%).After adding 0.1 wt.%Ce,the average grain size decreases from 98.9±5.7μm to 49.8±1.0μm,and the texture is significantly weakened.Further additions of Ce(0.3 and 0.5 wt.%)do not lead to significant alterations in the average grain size and texture intensity when compared with the NZ30K-0.1Ce alloy.Grain refinement is related to the constitutional supercooling,and the texture weakening is connected to the solid solubility of Ce in the Mg matrix.The ultimate tensile strength and elongation of NZ30K-0.1Ce alloy are 37.2% and 61.3% higher than those of NZ30K alloy.Grain refinement and texture weakening are the reasons for the better strength-ductility of NZ30K-0.1Ce alloy.展开更多
1000 MPa级高强钢在水电领域的应用已日趋成熟,但国内相应高性能焊材的研发较少,高强度熔敷金属保持低温高韧性是研发难点之一.通过添加Ce元素优化熔敷金属,并利用扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(tr...1000 MPa级高强钢在水电领域的应用已日趋成熟,但国内相应高性能焊材的研发较少,高强度熔敷金属保持低温高韧性是研发难点之一.通过添加Ce元素优化熔敷金属,并利用扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、高温激光共聚焦扫描显微镜(confocal laser scanning microscope,CLSM)等微观组织表征方法,研究了Ce含量对1000 MPa级高强钢埋弧焊熔敷金属组织强韧性及组织演变规律的影响.结果表明,Ce含量为0.02%时,抗拉和屈服强度分别提高3.7%和17.2%,此时强韧匹配效果最好,低温冲击韧性整体提升,Ce含量为0.01%时提升最大,-40℃和-60℃环境下分别为24.3%和42.2%.微观组织方面,Ce可细化晶粒,使M-A组元分布更弥散,增强组织韧性;含量为0.04%时会使块状铁素体和针状铁素体尺寸变大、大尺寸晶粒增多,影响抗拉强度.演变机理上,Ce与C协同富集引发晶格畸变促进M-A组元生成,含量为0.02%时使残余奥氏体含量增加,借助相变诱发塑性(transformationinduced plasticity,TRIP)效应提升塑性变形能力,促进下贝氏体转变实现强韧性协同提升;0.04%的Ce则导致晶界偏析加剧,形成含Ce脆性相析出物,降低奥氏体稳定性,使冲击韧性相对于0.02%时劣化.展开更多
基金financially supported by the National Natural Science Foundation of China[Grant No 52305341,U2341253,52371019]the Basic Scientific Research Project of Liaoning Provincial Education Department[JYTQN2023003].
文摘Grain size and texture can be controlled to improve the strength and ductility of magnesium rare-earth(Mg-RE)alloys by alloying.Directed energy deposition-arc(DED-arc)is a typical sub-rapid solidification process that contributes to the modification of the microstructure.In this paper,a series of novel Mg-3.0Nd-0.2Zn-0.3Zr-xCe(NZ30K-xCe)alloys with different Ce contents(0,0.1,0.3,0.5 wt.%)were prepared by DED-arc.The results show that the experimental alloys have lower porosity(≤0.11%).After adding 0.1 wt.%Ce,the average grain size decreases from 98.9±5.7μm to 49.8±1.0μm,and the texture is significantly weakened.Further additions of Ce(0.3 and 0.5 wt.%)do not lead to significant alterations in the average grain size and texture intensity when compared with the NZ30K-0.1Ce alloy.Grain refinement is related to the constitutional supercooling,and the texture weakening is connected to the solid solubility of Ce in the Mg matrix.The ultimate tensile strength and elongation of NZ30K-0.1Ce alloy are 37.2% and 61.3% higher than those of NZ30K alloy.Grain refinement and texture weakening are the reasons for the better strength-ductility of NZ30K-0.1Ce alloy.
