高温形变对FeCoCrMoYCB块体非晶结构和热稳定性的影响

Effect of high temperature deformation on structure and thermal stability of FeCoCrMoYCB bulk amorphous alloy

采用水冷铜模吸铸法制备直径为4 mm的Fe_(41)Co_7Cr_(15)Mo_(14)Y_2C_(15)B_6块体非晶合金,利用X射线衍射(XRD)和差式扫描量热分析仪(DSC)分别对该非晶的结构及热力学参数进行表征。利用Gleeble 3500热模拟机在过冷液相区温度620℃下,以1×10^(-2)s^(-1)的应变速率对该非晶合金进行压缩变形,研究变形量(20%、40%和75%)对该非晶合金结构和热稳定性的影响。结果表明,该条件下非晶试样能发生较好的塑性变形并未发现明显的晶化,且随着塑性变形的增加,非晶合金的热稳定性更加优异,当形变量为75%时,非晶合金的玻璃转变温度和过冷液相区宽度分别从铸态的585℃和40℃增大至658℃和59℃。变形影响非晶试样的显微硬度,宏观表现为应变量越大其显微硬度越高,当塑性形变量为20%、40%及75%时,对应最高维氏硬度分别为1258,1270和1288 HV。

Fe41Co7Cr15Mo14Y2C15 B6 bulk metallic glass （BMG） with a diameter of 4 mm was prepared by water-cooled copper mold suction method, and the amorphous feature and thermodynamic parameters of the as-cast alloy were analyzed by means of X-ray diffraction （XRD） and differential scanning calorimeter （DSC） , respectively. Compression test in supercooled liquid region for the amorphous alloy was carried out on a Gleeble 3500 thermal simulator at 620 ℃ and strain rate of 1 × 10-2s-l, and the effect of different deformations （20% , 40% and 75% ） on the microstructurc and the thermal stability of the amorphous alloy was investigated. The results show that the samples exhibit a good ductility without obvious crystallization at this condition, and the thermal stability of the amorphous alloy becomes more excellent with the increase of the plastic deformation, especially, when the plastic strain is 75% , the glass transition temperature and the width of the supercooled liquid region increase from original 585 ℃ and 40 ℃ to 685 ℃ and 59 ℃ , respectively. The microhardness of the amorphous alloys increases with the increase of deformation. When the deformations are 20% , 40% and 75% , the highest vicker hardness of the amorphous alloy are 1258, 1270 and 1288 HV, respectively.