冷轧变形Pb-Ca-Sn-Al合金在回复和再结晶过程中的晶界特征分布

GRAIN BOUNDARY CHARACTER DISTRIBUTIONS (GBCD) OF COLD-ROLLED Pb-Ca-Sn-Al ALLOY DURING RECOVERY AND RECRYSTALLIZATION

采用电子背散射衍射(EBSD)技术研究了冷轧变形Pb-0．1％Ca-1．5％Sn-0．026％Al合金在回复和再结晶过程中的晶界特征分布(GBCD)．结果表明:在回复过程中,合金内形成了比例接近50％的平直∑3晶界,这类晶界不处在由一般大角度晶界构成的晶界网络上,不能使合金的GBCD得到优化;相反,在再结晶过程中,除了生成比例超过50％的∑3晶界外, 还出现了较多的∑9和∑27等低∑重位点阵晶界(CSL),并且这些晶界和相当多的弯曲的∑3晶界均处在由一般大角度晶界构成的晶界网络上,可以使合金的GBCD得到优化．进一步的分析指出:回复过程中所形成的平直的∑3晶界是共格孪晶界, 它们能量很低,很难迁移;在再结晶过程中,除了生成不可迁移的共格的∑3孪晶界外,还可形成大量可迁移的弯曲的非共格∑3 晶界,这类晶界的迁移和彼此会合可形成∑9和∑27等∑3n(n为正的整数)晶界,这是合金GBCD得到优化的根源．

Grain boundary character distributions （GBCD） of cold-rolled Pb-Ca-Sn-Al alloy during recovery and recrystallization were investigated by means of electron back scatter diffraction （EBSD）.The results indicate straight ∑3 boundaries of near 50% （length fraction of total boundary） are introduced in the alloy during recovery. Such boundaries are not distributed in the network of general high angle boundaries （HABs） and the GBCD are not optimized. Conversely, in the recrystallization, apart from ∑3 boundaries of over 50% , a fair amount of ∑9 and ∑27 coincidence site lattice （CSL） boundaries appeared, which along with a great deal of curved ∑3 boundaries are located in the network of HABs and the GBCD are optimized. The straight ∑3 boundaries are stable and immobile （111）60° coherent twin boundaries, while the curved ∑3 boundaries are nearly incoherent. The migration of incoherent ∑3 boundaries as well as the interaction between them result in the formation of ∑9, ∑27 and other ∑3^n（n is a positive integer） boundaries, which is the root of GBCD optimization.