Ductility and fracture behavior of polycrystalline Ni/sub 3/Al alloys

Conference · Wed Jan 01 00:00:00 UTC 1986

OSTI ID:7123206

Liu, C T

This paper provides a comprehensive review of the recent work on tensile ductility and fracture behavior of Ni/sub 3/Al alloys tested at ambient and elevated temperatures. Polycrystalline Ni/sub 3/Al is intrinsically brittle along grain boundaries, and the brittleness has been attributed to the large difference in valency, electronegativity, and atom size between nickel and aluminum atoms. Alloying with B, Mn, Fe, and Be significantly increases the ductility and reduces the propensity for intergranular fracture in Ni/sub 3/Al alloys. Boron is found to be most effective in improving room-temperature ductility of Ni/sub 3/Al with <24.5 at. % Al. The tensile ductility of Ni/sub 3/Al alloys depends strongly on test environments at elevated temperatures, with much lower ductilities observed in air than in vacuum. The loss in ductility is accompanied by a change in fracture mode from transgranular to intergranular. This embrittlement is due to a dynamic effect involving simultaneously high localized stress, elevated temperature, and gaseous oxygen. The embrittlement can be alleviated by control of grain shape or alloying with chromium additions. All the results are discussed in terms of localized stress concentration and grain-boundary cohesive strength. 55 refs., 10 figs., 3 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7123206
• Report Number(s): CONF-861207-58; ON: DE87005340
• Conference Information: Materials Research Society fall meeting, Boston, MA, USA, 1 Dec 1986
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals &amp; Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
BERYLLIUM ADDITIONS
BERYLLIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
CRYSTAL STRUCTURE
DOCUMENT TYPES
DUCTILITY
ELEMENTS
EMBRITTLEMENT
FRACTURE PROPERTIES
GRAIN BOUNDARIES
INTERMETALLIC COMPOUNDS
IRON ADDITIONS
IRON ALLOYS
MANGANESE ADDITIONS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
NONMETALS
OXYGEN
REVIEWS
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES