含铟的铜基补口合金对925银性能的影响

Effect of Copper-base Master Alloy Contain Indium on the Properties of 925 Silver

添加质量分数为0%、2%和4%的铟制备铜基补口合金,随后采用失蜡铸造工艺制备925银饰品合金。通过测试925银合金铸态物理性能、对比研究微观组织。结果表明,采用添加铟元素的铜基补口合金制备的925银合金熔点降低,液固相线温差缩小,流动性提高;微量铟对925银合金起到变质作用,细化组织晶粒,促进生成初生枝晶,拉伸强度及显微硬度均略有提高;微观组织中枝晶被高铟相圈包裹,当补口合金中铟含量为4%时,枝晶底部产生颈缩,形成游离孪晶组织。

The copper-based master alloy for precision casting was prepared by adding indium in mass fraction of 2%and 4%.925 silver jewelry alloy was manufactured by using the lost wax casting process,and then was tested for its physical property and microstructure.The results show that the addition of indium will lower the melting point of 925 silver alloy and narrow the temperature difference between liquid and solid phase lines and increase the fluidity.Traces of indium play a role in metamorphism of 925 silver alloy,and will refine the grain structure,promot the formation of primary dendrites.The tensile strength and micro-hardness are improved slightly by using the copper-based master alloy added with indium element and the dendrite is wrapped by high indium-phase circle.If the indium content in master alloy is increased to 4%,the dendrite bottom will contract,producing a free twinning structure.