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Influence of Structure on the Microhardness of Ni3Al

Saida R. Idrisova ,  A. V. Korznikov 

Institute for Metals Superplsticity Problems, Russian Academy of Sciences, Ufa, Russian Federation


Influence of structure on the microhardness of Ni[3]Al
S.R. Idrisova, Institute for Metals Superplasticity Problems,
Khalturina 39, 450001 Ufa, Russia and A.V. Korznikov, Institute for
Metals Superplasticity Problems, Khalturina 39, 450001 Ufa, Russia.
Entirely disordered nanocrystalline (NC) structure with a grain size
of about 20 nm was formed in intermetallic compounds Ni[3]Al and
Ni[3]Al+B by high-pressure torsion on Bridgman anvil-type units. After
step by step annealing of NC Ni[3]Al and Ni[3]Al+B specimens in the
temperature range 353-1313 K (each step was equal to 60 K) the data of
microhardness, average grain size, long-range ordering parameter,
internal stresses were obtained. Mechanical properties and fracture
surfaces were studied at three-point bending tests. The contribution
of each structure characteristic and the influence of boron
microalloying on microhardness of Ni[3]Al depending on temperature of
annealing were estimated qualitatively by suing the data obtained. The
comparative analysis of these data and qualitative estimation of the
influence of different structure characteristic on microhardness
Ni[3]Al were made. It is assumed that deformation of NC materials is
localized in grain boundaries (GB) and realized via a large number of
small micro-shears.
It is shown that deformation of NC Ni[3]Al is performed by a shear
mechanism and the decrease in cohesive strength of GB in the process
of long-range ordering leads to the decrease of plasticity to zero.
Boron microalloying slightly enhances plasticity of NC Ni[3]Al,
however due to extension of GB area the concentration of boron in them
is smaller than in coarse-grained analogues.


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Related papers

Presentation: poster at E-MRS Fall Meeting 2002, by Saida R. Idrisova
See On-line Journal of E-MRS Fall Meeting 2002

Submitted: 2003-02-16 17:33
Revised:   2009-06-08 12:55