scholarly journals Deformation Twinning in Ordered Intermetallic Compounds

1988 ◽  
Vol 133 ◽  
Author(s):  
M. H. Yoo ◽  
C. L. Fu ◽  
J. K. Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Intermetallic Compounds ◽  
Deformation Twinning ◽  
Intermetallic Alloys ◽  
High Temperature Mechanical Properties ◽  
Ordered Intermetallic ◽  
Specific Calculations ◽  
Superlattice Structures

ABSTRACTMechanistic understanding of deformation twinning in ordered superlattice structures is reviewed, and the inter-relationships between twinning and generalized plastic flow or fracture toughness are discussed. While general discussions refer to all the fcc-based and bcc-based cubic and noncubic ordered intermetallic alloys, specific calculations of the energetic and kinetic aspects of deformation twinning are made for TiAl. The importance of the twin-slip conjugate relationship on high temperature mechanical properties is emphasized. Discussion is given of possible effects of macro- and micro-alloying on twinning propensity.

The disordering process in an Ll2 ordered alloy

1984 ◽  
Vol 42 ◽  
pp. 486-487
Author(s):  
J. A. Horton ◽  
A. DasGupta ◽  
C. T. Liu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Temperature ◽  
Intermetallic Alloys ◽  
Antiphase Boundaries ◽  
High Temperature Mechanical Properties ◽  
Heat Treated ◽  
Ordered Intermetallic

Ordered intermetallic alloys potentially have good high temperature mechanical properties which often are obtained by macroalloying. Since service temperatures may be near the critical ordering temperature, Tc, it is important to understand the disordering processes. The disordering mechanism in an alloy of 52.5 at. % Ni—22.5 Fe—14.5 V—10 Al—0.5 Ti [which can be expressed as (Ni70Fe30)3(V58Al40Ti2)], will be presented here. The aluminum was added to increase Tc from 750 to 975°C and stabilize the Ll2 structure.All specimens were first fully ordered by a heat treatment consisting of 30 min at 1000°C, 1 d at 700°C and 2 d at 600°C which results in a “swirl” pattern of antiphase boundaries (APB) similar to Fig. 1. Specimens were then heat-treated for 24 h at temperatures from 600 to 950°C in 50°C increments and water quenched.

Strength and Toughness of Be12Nb, Be17 Nb2 and Two-Phase Be12Nb-Be17Nb2

1992 ◽  
Vol 273 ◽  
Author(s):  
Stephen M. Bruemmer ◽  
Bruce W. Arey ◽  
Charles H. Henager
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Intermetallic Compounds ◽  
Compression Strength ◽  
Bend Strength ◽  
Two Phase ◽  
High Temperature Mechanical Properties ◽  
Strength And Toughness

ABSTRACTBend strength, compression strength, and fracture toughness of niobium beryllide intermetallic compounds have been assessed at temperatures from ambient to 1200°C. Hot-isostatically-pressed (HIP) Be12Nb showed significantly improved lowand high-temperature mechanical properties over vacuum-hot-pressed (VHP) material. Strengths at 20°C were 250 MPa in bending and 2750 MPa in compression with a fracture toughness of ∼4 Mpa√m, much higher than previously measured for this compound. High-temperature (≥ 1000°C) mechanical properties were also improved with bend strengths of 250 MPa at 1200°C as compared to only 70 to 100 MPa for the VHP material. However, severe pest embrittlement was detected in the HIP material at temperatures between 650 and 1000°C.

scholarly journals Influence of Boron Addition on High Temperature Mechanical Properties of Nb3Ir Intermetallic Compounds

2000 ◽  
Vol 41 (12) ◽  
pp. 1605-1611 ◽  
Author(s):  
Yi Tan ◽  
Chao-Li Ma ◽  
Hisao Tanaka ◽  
Akio Kasama ◽  
Ryohei Tanaka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Intermetallic Compounds ◽  
Boron Addition ◽  
High Temperature Mechanical Properties

High Temperature Ordered Intermetallic Alloys

1986 ◽  
Vol 81 ◽  
Author(s):  
D. P. Pope
Keyword(s):  
High Temperature ◽  
Intermetallic Compounds ◽  
Low Temperatures ◽  
Current Knowledge ◽  
Research Work ◽  
Complex Structures ◽  
Intermetallic Alloys ◽  
Laves Phases ◽  
Melting Temperatures ◽  
Ordered Intermetallic

AbstractThis paper is intended to be a general introduction to this conference and is therefore not a review of the state of our current knowledge. Instead, it will address questions like the following: Why are intermetallic compounds interesting? What alloys are being studied, and which are being ignored? Since most research work is now being performed on L12 alloys, with by far the greatest emphasis on Ni3Al, the balanceof the paper will concentrate on strengthening mechanisms and mechanisms of ductility control in Ni3Al, pointing out the interesting questions and controversies which arose during this conference.The conclusions to be drawn from this paper are that ordered intermetallic alloys are very valuable materials for high temperature use, but engineers probably must become more sophisticated in the use of materials with limited ductilities at low temperatures before intermetallics will gain widespread usage. Furthermore, additional research needs to be performed on more complex intermetallic compounds than L12 since L12 compounds, as a group, do not have particularly high melting temperatures. However,since alloys with complex structures, e.g. Laves phases, are well known for their brittleness at low temperatures, it is all the more important that the properties of such alloys be studied and methods found to improve their ductilities.

ZIRCONIUM GR. 32

Alloy Digest ◽  
1968 ◽  
Vol 17 (4) ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Cross Section ◽  
Neutron Cross Section ◽  
Heat Treating ◽  
High Temperature Mechanical Properties ◽  
Temperature Performance ◽  
Excellent Corrosion Resistance

Abstract ZIRCONIUM Gr. 32 is an alloy with a low neutron cross-section, good high temperature mechanical properties and excellent corrosion resistance in water and steam. It is a reactor grade zirconium-tin alloy for corrosion resistance in irradiated water. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Zr-4. Producer or source: AMAX.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

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