定向凝固Ag-28Cu-xNi系合金的组织和性能研究

Study on microstructure and properties of directionally solidified Ag-28Cu-xNi alloy

采用定向凝固技术,制备了Ag-28Cu-xNi(x=0、0.75、1.0、2.0)系4类合金棒材,采用金相显微镜、透射电镜、扫描电镜研究了合金的显微组织结构和断口形貌;采用万能电子实验机,研究了合金的力学性能。结果表明,定向凝固Ag-28Cu合金的显微组织为竖直生长的柱状晶组织,Ag-28Cu-0.75Ni合金的显微组织为不同方向生长的树枝晶组织,Ag-28Cu-1Ni和Ag-28Cu-2Ni合金的显微组织为块状+花瓣状枝晶组织。随着冷拉拔变形真应变从η=3.22逐渐增大到η=6.0,Ag-28CuxNi系合金呈现出抗拉强度逐渐升高、延伸率逐渐下降的变化趋势;Ni元素的添加使Ag-28Cu合金的硬度、强度和延伸率均有不同程度的减小。Ag-28Cu-0.75Ni合金的室温拉伸断口形貌呈现有明显的缩颈现象和大量的韧窝,其断裂机制为微孔聚集型塑性断裂。

Four types of alloy bars of Ag-28Cu-xNi(x=0,0.75,1.0,2.0)series were prepared using directional solidification technology.The microstructure and fracture morphology of the alloy were studied by metallurgical microscope,transmission electron microscope,and scanning electron microscope.Using a universal electronic experiment machine,the mechanical properties of the alloy were studied.The results show that the microstructure of the directionally solidified Ag-28Cu alloy is a vertically grown columnar crystal structure,the microstructure of the Ag-28Cu-0.75Ni alloy is a dendritic structure grown in different directions,and the microstructures of the Ag-28Cu-1Ni and Ag-28Cu-2Ni alloys are block+petals.Shaped dendrite organization.As the true strain of cold drawing deformation gradually increases fromη=3.22 toη=6.0,Ag-28Cu-x Ni alloys show a trend of increasing tensile strength and decreasing elongation;the addition of Ni makes the hardness of Ag-28Cu alloy,The strength and elongation have been reduced to varying degrees.The tensile fracture morphology of Ag-28Cu-0.75Ni alloy at room temperature shows obvious necking phenomenon and a large number of dimples,and its fracture mechanism is microporous aggregation type plastic fracture.