An Experimental Investigation On The Solubility And Dissolution Rate Of Zr In Cu-Sn Alloys

Zirconium content in the crust is very rich, more than copper, lead, zinc and othercommon elements. Zirconium metal and its alloys are widely used in aerospace,aviation, nuclear energy, electronics, metallurgy, chemicals, and medical industries.Particularly, the application of Zr in the nuclear industry is of great significance. Theexcellent performance of zirconium as structural materials in the core of nuclearreactor lies in its thermal neutron absorption cross section only0.18×10-28m2. But asthe main impurity in zirconium, hafnium has a large neutron absorption cross sectionwhich is harmful for the application of zirconium as core material of nuclear reactorand has to be eliminated from zirconium as possible as one can. There are manyprocesses for separation hafnium from zirconium were proposed and practiced. Eventhough, the purification processes of zirconium are still very complicated and highcost.In this paper, the dissolution rate and solubility of Zr in Cu-Sn alloys was studiedin a SiC high temperature furnace. Experiments were carried out in an Ar atmospherewith Zr crucible. The prepared Cu-Sn alloys were melted at a certain temperature inthe Zr crucible. During the experiment, the liquid alloys were extracted and quenchedin water. In addition the content of Zr was analyzed in those samples which changedwith the time, the composition of Cu-Sn alloys, and the temperature. Some of thesamples were also studied by means of XRD, DSC, scanning electron microscope andX-ray energy dispersed spectrum analysis.By changing the composition of Cu-Sn alloy and temperature of the experiment,the effect of the composition of Cu-Sn alloy and temperature at the differentexperimental conditions on the dissolution rate and solubility of Zr in the Cu-Sn alloywere investigated. It is concluded that:(1) The dissolution rate of Zr in the Cu-Sn alloys increases with increase of Cucontent of Cu-Sn alloy and temperature before the dissolution equilibrium. The experimental temperature has a significant effect on the dissolution rate of Zr in Cu-Snalloys.(2) At the beginning, the solubility of Zr in Cu-Sn alloys changes with thecomposition of the alloys at a certain temperature. When the temperature is900C andthe ratio of Cu to Sn is8:2, the maximum solubility of6.2mass%for Zr in Cu-Sn-Zralloy is obtained at present work at the temperature range of700C to900C.(3) The crystalline phase containing zirconium mainly includes: Zr5Sn3, SnZr,CuZr and Cu51Zr14, and the existence of ternary alloy phase was not confirmed in thepresent composition range of alloys.(4) Relative to pure Cu, a small amount of Sn addition to Cu-Sn alloy canincrease the solubility of Zr in Cu-Sn alloys.(5) When the temperature is1000C and the ratio of Cu to Sn is10:0, themaximum solubility of61.2mass%under this experimental conditions.