  Hot Isostatic Pressing was applied to synthesize bulk samples with diameter
up to 30 mm starting with Alfa Aesar magnesium diboride powder. HIPing at 2
kbar, 1000 C with cooling under pressure (DMCUP cycle) resulted in a fully
dense (or low porosity) material with a sharp superconducting transition and
critical current comparable with the best reported. Elastic constants were
measured using method of resonant ultrasound spectroscopy. Their values for
most dense samples (bulk modulus 142.5 GPa and Young's modulus 272.5 GPa) are
close to theoretically predicted values for solid magnesium diboride. Porosity
is resposible for lower values of elastic constants. Fracture toughness is
evaluated based on measurements of microhardness and elastic constants. Upper
critical field and irreversibility field are comparable with data for samples
sintered at 3 GPa. Microstructural propeties of HIPed smaples are responsible
for enhanced flux pinning. Method allows scaling of the size of the samples and
manufacture of complex shapes.

Superconductivity;Materials Science