Accession Number : ADA495363


Title :   The Analysis and Modeling of Phase Stability and Multiphase Designs in High Temperature Refractory Metal-Silicon-Boron Alloys


Descriptive Note : Final performance rept. 15 Mar 2006-30 Nov 2008


Corporate Author : WISCONSIN UNIV-MADISON BOARD OF REGENTS/RESEARCH SPONSORED PROGRAMS


Personal Author(s) : Perepezko, John H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a495363.pdf


Report Date : 27 Jan 2009


Pagination or Media Count : 46


Abstract : For high temperature application beyond the range of Ni-base superalloys, Mo-Si-B alloys with the ternary intermetallic, Mo5SiB2, T2, phase as a key microstructure constituent, offer an attractive property balance of high melting temperature, oxidation resistance and useful high temperature mechanical properties. The fundamental basis of the alloying behavior in T2 including the mutual solid solution with transition metals has been established in terms of the governing geometric and electronic factors. For non-stoichiometric compositions, constitutional defects such as vacancies for Mo-rich compositions control the homogeneity range and play a key role in the development of dislocation and precipitation reactions that directly impact high temperature structural performance. The sluggish diffusion rates within the T2 phase have also been quantified and applied to materials processing strategies. The materials design based on the phase stability, diffusion and defect structure analysis in the Mo-Si-B system can also be applied to the design of new multiphase high-temperature alloys with balanced environmental and mechanical properties.


Descriptors :   *REFRACTORY METAL ALLOYS , *NICKEL ALLOYS , *SILICON ALLOYS , *MOLYBDENUM ALLOYS , *BORON ALLOYS , OXIDATION RESISTANCE , SOLID SOLUTIONS , SUPERALLOYS , HOMOGENEITY , DEFECT ANALYSIS , DIFFUSION , STRUCTURAL ANALYSIS , HIGH TEMPERATURE , TRANSITION METALS , MECHANICAL PROPERTIES , MICROSTRUCTURE


Subject Categories : Properties of Metals and Alloys


Distribution Statement : APPROVED FOR PUBLIC RELEASE