BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:High resolution electron microscopy of superalloys - Dr. Catherine
  Rae\, Department of Materials Science and Metallurgy
DTSTART:20121123T140000Z
DTEND:20121123T150000Z
UID:TALK40960@talks.cam.ac.uk
CONTACT:Ms Helen Gardner
DESCRIPTION:Superalloys are Nickel based alloys containing substantial add
 itions of up to 12 elements used at well over half the homologous melting 
 temperature in the aerospace industry.  High-resolution scanning transmiss
 ion electron microscopy (HR STEM) in a variety of instruments including th
 e Titan microscope has been used to study the structure of dislocations an
 d other precipitates in both single crystal alloys for blade applications 
 and the discs which support their rotation. In single crystal High Pressur
 e turbine blades the first rotating part after the combuster the single cr
 ystal blades are cooled by a complex system of cooling channels and the lo
 ad is principally carried by the inner cores at temperatures of about 750
 ºC. Deformation in this temperature range is associated with extended dis
 locations cutting the coherent   precipitates. The study has reveale
 d the detailed structure of these dislocations as they shear and this has 
 important implications for the mobility of the dislocations. Another obser
 vation was the segregation of alloying elements with high atomic mass to t
 he stacking faults during shear.  In a newly-introduced polycrystalline di
 sc alloy Allvac718Plus\, High resolution microscopy has enable us to ident
 ify the details structure of precipitates added to inhibit the growth of g
 rains and improve the resistance to crack growth. These results reveal how
  and under what conditions these grains grow and assist in producing the o
 ptimum microstructures.
LOCATION:Oatley Seminar Room\, Department of Engineering
END:VEVENT
END:VCALENDAR