FGH95与Rene'95合金粉末热学凝固参数和微观组织

Comparison of Microstructures and Calculated Solidification Parameters Between FGH95 and Rene' 95 Superalloy Powders

摘要: 大量实验证明,铸态组织中二次枝晶臂距主要受冷却速度或凝固时间的影响。本文对FGH95和Rene’95氩气雾化的、不同粒度级的粉末颗粒测定了二次枝晶臂距,计算了冷却速度Ṫ、完成凝的固时间tf、凝固速度R及固—液界面前沿温度梯度G。结果表明:两种粉末粒度在-60—+320目范围内冷却速度为10³-10⁴℃/s,凝固时间为10^-1—10^-2s。随着粉末颗粒减小,冷却速度增加,G/R值增大,粉末颗粒的凝固从以树枝晶为主的方式逐渐转变成以胞状晶为主的方式,用G/R值来判断凝固组织中的碳化物形态不是唯一因素。

Abstract: Dendritic arms spacings of FGH95 and Rene'95 atomized powder for different mesh size were measured. Cooling rate (Ṫ) > local solidification time(t_f), thermal gradient (G), and growth rate (R) were calculated.It is shown that as local solidification time is 10^-1-10^-2s,cooling rate of two powders inside the range of -60-+320 mesh is 103-104℃/s.The cooling rate and O/R ratio inerease with decreasing particle size and dendrite structure of powder particle correspondly changes into cellular structure.It seems that the morphology of MC carbibe in powder particle does not depend only on O/R ratio.