FGH98合金的再结晶行为

Recrystallization behaviors of FGH98 alloy

利用扫描电镜和透射电镜对热挤压态和退火态FGH98合金的相析出规律及组织特征进行了分析,并对其再结晶机制进行了深入研究.结果表明:热挤压态FGH98合金在空冷过程中已经发生了少量的再结晶现象,随着挤压温度的提高,体系内位错密度下降.退火态FGH98合金中再结晶机制主要与体系内未回溶的一次γ'相有关,在一次γ'相聚集区再结晶主要以依靠亚晶的聚合和亚晶的长大,或两者的混合机制进行形核;随着一次γ'相的减少,合金还可以通过应变诱发晶界迁移、多晶粒交汇区形核、孪晶叠加等多种方式形核.需要指出的是,FGH98合金中未回溶的一次γ'相在退火处理过程中也会通过部分的回复和再结晶发生软化效应.

The precipitated phase behavior, microstructure characteristics and static recrystallization mechanisms of FGH98 alloy in extruding and annealing states were systematically investigated by scanning electron microscopy （ SEM ） and transmission electron microscopy （ TEM） . A portion of recrystallized grains were observed in as-extruded samples during the cooling process, and the dislocation density decreases with the increasing of deformation temperature. The recrystallization mechanism of FGH98 alloy during the annealing process is mainly dominated by residual primary γ′phase. In the region with a more content of residual primary γ′phase, static recrystallization is controlled by the coalescence and growth of subgrains;when residual primary γ′phase in the alloy decreases, many nucleation mechanisms of static recrystallization may occur, such as strain-induced boundary migration （ SIBM ） , nucleation in the juncture of several grains, and twins superposition nucleation. It must be pointed out that residual primary γ′phase in the alloy can also be softened to somewhat extent by recovery and recrystallization during the annealing process.