ISSN:
1662-9779
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Physik
Notizen:
The thermodynamic properties and phase transformations of metals and alloys are studiedusing the statistical moment method, going beyond the quasi-harmonic approximations. Includingthe power moments of the atomic displacements up to the fourth order, the Helmholtz free energiesand the related thermodynamic quantities are derived explicitly in closed analytic forms. Thethermodynamic quantities, like thermal lattice expansion coefficients, specific heats, Grüneisenconstants, elastic constants calculated by using the SMM are compared with those of othertheoretical schemes and the experimental results. The hcp-bcc structural phase transformationsobserved for IVB elements, Ti, Zr and Hf, are discussed in terms of the anharmonicity of thermallattice vibrations. The equilibrium phase diagrams are calculated for the refractory Ta-W and Mo-Tabcc alloys. In addition, the temperature dependence of the elastic moduli C11, C12 and C14 and thoseof the ideal tensile and shear strengths of the bcc elements Mo, Ta and W are studied: We alsodiscuss the melting transitions of metals and alloys within the framework of the SMM and estimatethe melting temperatures through the limiting temperature of the crystalline stability
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.138.209.pdf
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