Accession Number:

ADA370083

Title:

Theoretical Studies of the Electronic Structure and Mechanical Properties of Intermetallics

Descriptive Note:

Final progress rept. 1 Sep 93-31 Jan 97

Corporate Author:

CALIFORNIA STATE UNIV NORTHRIDGE DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s):

• Kioussis, Nicholas

Report Date:

1999-08-15

Pagination or Media Count:

9.0

Abstract:

It is now clear that the high temperature intermetallics have become a major focus of research effort -both experimental and theoretical- driven in large part by their potential for important aerospace applications at elevated temperatures. State-of-the-art first-principles total-energy electronic structure calculations based on the full-potential linear-muffin-tin-orbital method were employed to study systematically issues of metallurgical nature, such as bonding, cohesion and phase stability and the role of ternary additions on their electronic and mechanical properties. More specifically, we have investigated 1 The effect of impurities boron and hydrogen in Ni3 Al 2 The contrasting effect of boron and sulfur impurities on the ideal cleavage fracture 3 The variation of the elastic constants with chemical environment across the Ni3 XX Al, Si, Ga, Mn intermetallics and their correlation to plastic deformation and 4 The anisotropy of the antiphase boundary APB energy between the 001 and 111 slip planes, responsible for the anomalous temperature dependence of the yield strength.

Descriptors:

• *ELECTRONICS
• *MECHANICAL PROPERTIES
• *CLEAVAGE
• *INTERMETALLIC COMPOUNDS
• PLASTIC DEFORMATION
• THERMAL PROPERTIES
• LINEAR SYSTEMS
• ORBITS
• HIGH TEMPERATURE
• TENSILE STRESS
• ELASTIC PROPERTIES
• ALLOYS
• FRACTURE(MECHANICS)
• HYDROGEN
• ANISOTROPY
• CHEMICAL REACTIONS
• SULFUR
• YIELD STRENGTH
• BORON
• COHESION
• POLYCRYSTALLINE
• NICKEL COMPOUNDS

Subject Categories:

• Inorganic Chemistry
• Properties of Metals and Alloys
• Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE