Phase transformations in some hafnium-tantalum-titanium-zirconium alloys
- Oak Ridge National Lab., TN (United States)
- Army ARDEC, Picatinny Arsenal, NJ (United States)
Phase transformations in hafnium alloys are of interest as a means of achieving a material which exhibits flow softening and high localized strains during deformation at high strain rates. Hafnium transforms from a body-centered-cubic beta phase to a hexagonal alpha phase upon cooling below 1749{degrees}C. Hafnium-based alloys containing up to 17.5% Ti, up to 17.5% Ta, and up to 7.3% Zr by weight were button-arc melted and, in some cases, hot extruded to obtain a refined grain size. A number of alloys were shown to have beta solvus temperatures in the range of 1100 to 1300{degrees}C and showed evidence of a shear transformation upon water quenching. The Vickers microhardness of the quenched materials are typically above 350 HV as compared to 300 HV or less for materials with an alpha plus beta structure. Quenching dilatometry indicates a martensite start temperature of about 750{degrees}C for the Hf-7.5 Ta-10 Ti-1 Zr alloy and 800{degrees}C or more for the Hf-7.5 Ta-7.5 Ti-1 Zr alloy. Tensile tests at 1 s{sup {minus}1} strain rate show a constant ultimate tensile strength for temperatures up to 600{degrees}C for the above two alloys and a rapid decrease in strength with a further increase in temperature.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Department of the Army, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 554145
- Report Number(s):
- ORNL/CP-95025; CONF-971168-; ON: DE98001067; CNN: Project 1892-G056-A1; TRN: 98:000012
- Resource Relation:
- Conference: 1997 international conference on tungsten, refractory metals and alloys, Lake Buena Vista, FL (United States), 17-19 Nov 1997; Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
METALLURGICAL PROGRESS REPORT NUMBER 14 FOR THE PERIOD OF JANUARY 1, 1962 TO MARCH 31, 1962
Recent observations of phase transformations in a U--Nb--Zr alloy