ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Phase separation of γ (A1) supersaturated solid solution into A1, γ’ (L12) and γ” (D022)phases was investigated in two Ni-rich Ni-V-Si ternary alloys by means of transmission electronmicroscopy. When the alloys are annealed at 1073K, two different sequences of the phase separationare observed, depending on the chemical composition of the alloy: In Ni-17.0at%V-6.9at%Sialloy (A) at the D022 corner of three-phase field, first many D022 particles precipitate aligning alongthe 〈110〉 direction of the matrix and the so-called chessboard pattern is observed, followed by theformation of L12 phase at the interface between D022 and A1 phases. In Ni-12.1at%V-11.3at%Sialloy (B) at the L12 corner of the Gibbs triangle, cuboidal L12 particles precipitate arranging alongthe 〈100〉 direction, and then D022 phase is formed. As the phase separation proceeds, a selectivegrowth/formation of the third phase (L12 in the alloy A, D022 in the alloy B) occurs: In the alloy A,L12 phase grows into D022 particle inside along the diagonal direction of D022 cube which is parallelto the a-axis of D022 tetragonal phase. In the alloy B, D022 forms on the {100} cube face of cuboidalL12 particle, arranging the c-axis of D022 perpendicular to the {100} cube face of L12 phase. As aresult of such a selective growth/formation, the first phase D022/L12 is split off into two particles,which results in the formation of laminated structure consisting of D022 and L12 phases. The selectivegrowth/formation is considered to occur so as to maintain the less elastic strain state
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.3036.pdf
Permalink