Ag-In-Cd合金辐照后的微观组织变化

Ag-In-Cd合金在核电站压水堆控制棒中广泛使用,其辐照肿胀行为是评价Ag-In-Cd控制棒使用寿命的关键因素。本文通过制备不同成分的模拟合金,来模拟Ag-In-Cd合金在堆内辐照后的成分变化,分析合金的密度及微观组织特点。结果发现,当Ag含量低至77.5%(质量分数)时,合金会分解为fcc和hcp两相,fcc相中贫Sn高Ag,hcp相中富Sn低Ag。当Ag含量在55%~61%之间时,合金以hcp单相存在。由实测的密度拟合出了合金密度随成分变化的关系式。此结果对于理解和掌握Ag-InCd合金的辐照肿胀行为有重要意义。

Microstructure Change of Ag-In-Cd Alloy after Irradiation in Reactor

Ag-In-Cd control rods are widely used in PWR nuclear power plants. The irradiation swelling behavior of Ag-In-Cd alloy is very important to the safety assessment of control rod during its operation. In this work, to simulate the change of microstructure and density of Ag-In-Cd alloy after irradiation in reactor, a series of simulation alloys were prepared, and the effect of composition on the microstructure and density was investigated. A formula to calculate the alloy density with different compositions was obtained by fitting the experimental values. It is found that simulation alloy will consist of two phases, an fcc phase and an hcp phase, when the content of Ag was 77.5% (mass fraction). In the fcc phase, Ag content will be higher than its average content, and there is a little amount of Sn. In the hcp phase, Ag content will be below its average content, and Sn content will be relatively high. After irradiation, Ag-In-Cd alloy will be single hcp phase when Ag content is between 55% and 61%.