添加Zr对快速凝固CuCr29合金液相分解微观组织的影响

Effects of Zr Addition on the Liquid Phase Separation in CuCr29 Alloys

使用限速熔体快淬技术研究了添加Zr对CuCr29合金液相分解微观组织的影响。研究结果表明,添加Zr可以有效地抑制快速凝固CuCr29合金的液相分解行为。当Zr元素的添加量大于1.0at%,快速凝固CuCr29合金的液相分解微观组织明显地得到细化。EDS分析和微观组织观察都表明,添加Zr元素后,在合金组织中只存在着富Cu基体和富Cr相,Zr元素以固溶形式影响着CuCr合金的凝固行为。由热力学分析可知,在CuCr29合金中添加Zr会降低过冷CuCr液体的混合自由能和液相分解的驱动力,从而增加液/固转变临界过冷度,使临界形核半径减小和形核速度增加,则快速凝固CuCr29合金的液相分解微观组织得到细化。

A limited rapid solidification technology was used to study the liquid phase separation in CuCr or CuCrZr alloy. The liquid phase separation in CuCr29 alloy can be restrained by Zr addition. When the amount of Zr addition is more than 1.0 at%, the restrained effects are remarkable. The EDS results and the microstructures reveals that when Zr element was added, there are also a Cu-rich phase and a Cr-rich phase in their microstructures, the effect of Zr on the solidification behavior of CuCr alloy is in solute. The thermodynamic analyses indicate that the mixing Gibbs free energy of super-cooled Cu-Cr melts and the driving force of liquid phase separation could be decreased by Zr addition. Because the critical supercooling of the liquid/solid transformation is increased, the critical radius of nucleation is decreased and the rate of nucleation is increased, the microstructure from liquid phase separation in CuCr29 alloy with rapid solidification is refined.