Dispersion/Solution Strengthening of Molybdenum at High Temperatures

• Published in: Materials and manufacturing processes 1994-11, Vol.9 (6), p.1143-1154
• Main Authors: Luo, Anhua, Jacobson, Dean L., Park, John J., Tsao, Bang H., Ramalingam, Mysore L.
• Format: Article
• Language: English
• ISSN: 1042-6914; 1532-2475
• DOI: 10.1080/10426919408934981

Tensile properties of pure molybdenum, a molybdenum - 0.5 at % hafnium carbide, and a molybdenum - 5 at % rhenium - 0.5 at % hafnium carbide were evaluated with a strain rate of 10'Vsec over a temperature region of 1200 to 2400 K in ultrahigh vacuum. The yield strengths, tensile strengths, solution and dispersion strength increments, strain-hardening exponents, and tensile elongations of these materials were determined. The effects of rhenium, hafnium carbide, and temperature on the tensile properties of molybdenum were examined. The fine size and superior thermostability of hafnium carbide: dispersoids resulted in a strong pinning effect on dislocations at high temperatures. Dispersion strengthening by hafnium carbide particles was significant in the entire temperature range employed. Solution strengthening by rhenium was effective up to approximately 1800 K. The microstructures of the post-test molybdenum-base alloys were characterized with a scanning electron microscope and a transmission electron microscope. The dominant deformation mechanism of these alloys was found to be dislocation sliding up to 1800 K. and was grain-boundary sliding at higher temperatures. The dominant strengthening mechanisms involved in these alloys included the long-range and the short-range interactions between the hafnium carbide dispersoids and the dislocations.