Ordered omega derivatives in (Zr3Al)-Nb alloys

被引：0

作者：

Tewari, R ^{[1
]}

Dey, GK ^{[1
]}

Mukhopadhyay, P ^{[1
]}

Banerjee, S ^{[1
]}

Bendersky, LA ^{[1
]}

机构：

[1] Bhabha Atom Res Ctr, Div Mat Sci, Bombay 400085, Maharashtra, India

来源：

PHASE TRANSFORMATIONS AND SYSTEMS DRIVEN FAR FROM EQUILIBRIUM | 1998年 / 481卷

关键词：

D O I：

暂无

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Various kinds of phase transformations, viz., spinodal decomposition, omega transformation, precipitation reactions and martensitic transformation can be induced in ternary (Zr3Al) -Nb alloys in conditions far removed from equilibrium. Transformation sequences in alloys containing 3% niobium are described and rationalized in terms of some basic tendencies such as phase separation and chemical ordering in the beta (bcc) phase and displacive omega and beta to cr (hcp) transformations. Microstructures of rapidly solidified alloy showed a distribution of cuboidal ( D8(8) phase) particles in the beta matrix. The periodic arrangement of these particles along the <100>(beta) directions was indicative of a spinodal transformation which preceded their formation. The beta -->D8(8) transformation could be accomplished by the superimposition of three processes, namely, chemical ordering, lattice collapse akin to omega transformation and vacancy ordering. During isothermal aging the D88 phase transformed into the B8(2) phase. The observed lattice correspondence and transformation morphology suggested that the D88 to B82 structural change involved the replacement of structural vacancies in the former by zirconium atoms without any reconstitution of the lattice. The evolution of the equilibrium Zr3Al (L1(2) structure) phase during prolonged aging were also studied.

引用

页码：321 / 326

页数：6