Accession Number : AD0875947

Title :   Crack Propagation Studies in Beryllium Single Crystals and Calculations of Solubility Limits in Dilute Beryllium Alloys.

Descriptive Note : Final technical rept. 1 Mar 69-31 Jul 70,

Corporate Author : FRANKLIN INST RESEARCH LABS PHILADELPHIA PA

Personal Author(s) : Damiano, V. V. ; Lalevic, B. ; London, G. J.

Report Date : AUG 1970

Pagination or Media Count : 151

Abstract : Crack propagation was studied in three purity levels of beryllium single crystals. Cracks were initiated at the base of a notch and propagated on the (0001) and (11-20)0 planes. The effect of temperature on the propagation and blunting of cracks was examined. The propagation of cracks on the (0001) plane is less sensitive to purity than propagation on the (11-20) planes. Although cracks on readily propagated on the (0001) planes in high purity beryllium at 350C they are easily blunted at room temperature on the (11-20) plane. The band structure energy was computed as a function of the axial c/a ratio for hcp metal such as Be, Mg and Zn and for their dilute alloys with Cu, Ag, Au and Li. A theoretical criterion was obtained for the solubility limits for hcp metals, which is in agreement with experiments. It was found that in order to form a ternary alloy with Be-Cu, the third element should have a very broad form factor such as in thallium or indium. It was demonstrated the stability of hcp phase of Be and Mg and their dilute alloys and shown that fcc structure and at the formation of stacking faults is quite unlikely in Be-Cu alloy. Finally, a method was obtained to judge the validity of the different forms of pseudopotential and thus come closer to the explanation of the observed phase diagrams of metals. (Author)

Descriptors :   (*BERYLLIUM, CRACK PROPAGATION), (*BERYLLIUM ALLOYS, BAND THEORY OF SOLIDS), SINGLE CRYSTALS, SOLUBILITY, STABILITY, MICROSTRUCTURE.

Subject Categories : Properties of Metals and Alloys
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE