摘要
施加脉冲电流进行Ti-45.5Al-4Cr-2.5Nb(原子分数,%)合金的定向凝固并结合仿真实验,研究了脉冲电流对其凝固组织和性能的影响。结果表明:随着频率为200 Hz的脉冲电流密度的增大电流集肤效应增强、熔体内电流集肤效应加重。在集肤层电流焦耳热效应的作用下糊状区侧向散热的热流密度降低,使枝晶的平均偏离角减小,从而使合金的断后延伸率增大。脉冲电流密度较小时,在焦耳热效应和电磁搅拌的作用下熔体中枝晶的重熔和破碎使柱状晶晶粒的径向尺寸减小。但是,过量的焦耳热使熔区的长度增大、温度梯度减小,反而使晶粒的径向尺寸增大。因此随着电流密度的增大TiAl合金的抗拉强度先提高后降低,施加频率为200 Hz、电流密度为35.3 m A/mm的脉冲电流Ti Al合金的抗拉强度最大,比母合金铸锭的抗拉强度提高了70.7%。电流密度为52.9 m A/mm时延伸率达到最大值,比母合金锭的延伸率提高了129.5%。
Referring to the simulation results,the effects of pulse current with different parameters on the solidification structure and properties of directionally solidified Ti-45.5Al-4Cr-2.5Nb(%,atom fraction)alloy were investigated.The results show that when the pulse current frequency is 200 Hz,due to the skin effect of current and Joule heat effect of current the surface current of melt is biased and the lateral heat dissipation decreases,the average deviation angle of dendrite decreases,and the elongation increases with the decrease of deviation angle.When the density of pulse current is small,the average width of grains decreases with the increase of current density due to Joule heat effect of current and electromagnetic stirring which promote the remelting or breaking of dendrites.However,when the current density reaches a certain value,the melting zone grows up and the temperature gradient decreases.On the contrary,the average width of grains increases and the tensile strength of TiAl alloy first increases with the increase of current density,and then decreases;Compared with the master alloy ingot,the tensile strength and elongation of TiAl alloy increased by 70.7%and 129.5%respectively.
作者
王国田
龙泽堃
吴彪
王强
丁宏升
WANG Guotian;LONG Zekun;WU Biao;WANG Qiang;DING Hongsheng(School of Automobil and Traffic Engineering,Heilongjiang Institute of Technology,Harbin 150050,China;National Key Laboratory for Precision Hot Processing of Metals,School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China)
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2022年第9期706-714,共9页
Chinese Journal of Materials Research
基金
黑龙江工程学院博士基金(2019BJ03)
黑龙江工程学院基本科研业务费(创新团队类)项目(2020CX02和2018CX07)
省领军人才梯队培育计划(2020LJ04)
黑龙江省自然科学基金(LH2019E114)。
关键词
金属材料
脉冲电流
TIAL合金
定向凝固
微观组织
力学性能
metallic materials
pluse current
TiAl alloy
directional solidification
microstructure
mechanical property
