Cu-Ni-Sn扩散偶的界面过渡层固相序列分析

Solid Phase Transition Layer Sequences of Cu-Ni-Sn Diffusion Couple Interface

铍铜合金性能优异,但潜存毒性危害,Cu-Ni-Sn合金是一种典型的调幅分解强化型弹性铜合金,凭借其高的强度、硬度、弹性和优良的抗应力松弛性能,广泛应用于电子、航天、航海等领域,是替代铍铜的候选材料之一。然而Cu-Ni-Sn合金体系复杂,不同成分合金的性能差异较大,传统的研究材料的方法,一次只能研究一种或几种成分的合金,因此本文选择了"扩散多元节"高通量实验方法对Cu-Ni-Sn合金进行研究。本文采用CALPHAD相图计算手段,计算了Cu,Ni和Sn元素在相变过程中的活度变化曲线,根据元素活度在合金相中的范围大小对Cu-Ni-Sn三元扩散偶的Cu-Ni,Cu-Cu35Sn和Ni-Cu35Sn各个界面的固相序列进行了理论优化。通过Cu-Ni-Sn三元扩散偶实验,获得了CuNi,Cu-Cu35Sn和Ni-Cu35Sn扩散界面的过渡层组织形貌,结合理论计算结果,得到了可能的界面固相序列。在650℃条件下,Cu-Ni界面处仅有fcc_A1相的过渡层;Cu-Cu35Sn界面过渡层固相序列自富Cu端为fcc_A1→D03_Cu3Sn/Cu3Sn;Ni-Cu35Sn界面的固相序列自富Ni端为fcc_A1+Ni3Sn_LT→fcc_A1+Ni3Sn2→Ni3Sn2+D03_Cu3Sn/Cu3Sn。

Beryllium copper elastic alloys showed excellent properties,but there existed the underlying danger of poisonousness.With high strength,excellent elasticity and good anti-stress relaxation properties,Cu-Ni-Sn alloys were widely used in electronics,information,aerospace,and other industries,which made Cu-Ni-Sn alloys become an ideal alternative material of the Cu-Be alloy.However,the Cu-Ni-Sn alloy system was very complicated,the properties of the alloys were heavily affected by the composition,and the traditional methods could study only one or two kinds of alloy,so a diffusion multiples,high-throughout method was chosen to research the Cu-Ni-Sn alloy.The activities of Cu,Ni,Sn during the phase transitions were calculated by CALPHAD approach.The solid phase transition layer sequences of Cu-Ni,Cu-Cu35 Sn,Ni-Cu35 Sn interfaces in the Cu-Ni-Sn diffusion couple were optimized theoretically based on the range of element activity,respectively.The morphology of each interface was observed from the Cu-Ni-Sn ternary diffusion couple experiment and the possible interface solid phase transition layer sequences were obtained finally,combined with the calculated results.It was indicated that the unique fcc_A1 phase transition layer existed in the Cu-Ni binary interface at 650 ℃.The solid phase transition layer sequence of Cu-Cu35 Sn interface from the Cu-rich side was fcc_A1→D03_Cu3Sn/Cu3 Sn.And the solid phase transition layer sequence of Ni-Cu35 Sn interface was fcc_A1 ＋ Ni3Sn_LT →fcc_A1 ＋ Ni3Sn2→Ni3Sn2＋ D03_Cu3Sn/Cu3 Sn.