Mechanical properties of microcrystalline Ni3Al intermetallic alloy

Pawel JOZWIK ,  Zbigniew BOJAR ,  WOJCIECH PRZETAKIEWICZ 

Military University of Technology (WAT), Kaliskiego 2, Warszawa 00-908, Poland

Abstract

A significant influence of heat and thermo-mechanical treatment and additional plastic working parameters on structure and properties of two-phase (gamma prim + gamma) Ni3Al (Zr, B) intermetallics with zirconium and boron was shown in this paper.
As a result of long-lasting heat annealing at the temperature up to 1473 K, in duration up to 100-hours on effective modification of structure homogeneity (up to single gamma prim phase) and mechanical properties (tensile strength and yield point on the level of 700MPa and 300MPa adequately in as-cast, and 600MPa and 200MPa after annealing at 1273K/50h/air).
Using optimalized parameters of plastic and thermo-mechanical treatment, over 1000-times refinement of grains was obtained in investigated alloy (from irregular - shape crystals of 4 mm in linear dimension to 4 micrometers in diameter polyhedral grains). It was shown that fine- grained structure of investigated intermetallic alloy results in their plastifying. On the samples of fine - grained alloy it was confirmed that fractures occurred during tensile testing were ductile, the proof stress was low and the tensile strength was quite high (in chosen cases of Ni3Al based intermetallics after processing, the proof stress of 400MPa, the tensile strength of 1400MPa and over 50% unit elongation during tensile testing at room temperature were recorded).
Possibility to strengthening of fine-grained Ni3Al by cold rolling up to 50% reduction ( 100% reduction is also possible). Thin foils with thickness below of 0,4 mm without cracking were obtained. The yield point over 2200MPa, tensile strength over 2300MPa and unit elongation about 2% during a tensile testing at room temperature, in air were obtained for the material a such strengthened condition.
Singes of fracture by shear as results of tensile testing were shown and the fractures obtained were ductile.

 

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Presentation: poster at E-MRS Fall Meeting 2004, Symposium H, by Pawel JOZWIK
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-07-22 17:56
Revised:   2009-06-08 12:55