电子束区熔定向凝固Ni-Si共晶合金的固-液界面演化规律

Solid/liquid interface evolution of the directionally solidified Ni-Si eutectic alloy with electron beam floating zone melting technique

采用电子束悬浮区熔定向凝固技术制备了Ni-Ni3Si共晶自生复合材料,在稳态晶体生长区,采用零功率法获取了不同凝固速率的固-液界面。研究表明,随凝固速率的增大,固-液界面的形态发生了明显的变化。在凝固速率较低时,固-液界面基本保持平界面,形成的是规则的层片状共晶组织。随凝固速率的增大,成分过冷增大,平界面失稳,凝固组织的规则性也降低。此外,根据M-S界面稳定性判据,计算了不同凝固速率不同干扰波长对固-液界面稳定性的影响,理论计算与实验结果基本吻合。

Ni-Ni3 Si eutectic in situ composites were prepared by electron beam floating zone melting technique.The solid/liquid interface at different solidification rates were obtained by zero power method.It was shown that the morphologies of the solid/liquid interface changed obviously.At the low solidification rate(R ≤1.0 mm/min),the solid/liquid interface was planar interface.The planar interface was destroyed with the increase of the constitutional undercooling resulted in the increase of the solidification rate,and the regularity of the solidification microstructure was decreased as well.Moreover,the effect of wavelength of the interference wave on the stability of the solid/liquid interface was calculated according to M-S theory,the calculated result was consistent with the experimental result well.