Skip to main content
placeholder image

Formation of nanocrystalline cubic (L12) titanium trialuminide by controlled ball milling

Journal Article


Abstract


  • Pre-alloyed, as-cast ingots of the Mn-modified, cubic (L12) titanium trialuminide (65at% Al, 25·6at% Ti and 9·4at% Mn) were homogenized (1000deg;C/100), crushed into a coarse-particle powdered material and subsequently ball milled for up to 386h under shearing mode in a controlled ball movement mill. X-ray spectra of milled powders showed line broadening and decrease in intensity of Bragg peaks with increasing milling time. This is associated with the formation of nanocrystalline grains and lattice strains upon milling. Crystallite size calculated from peak broadening, remains relatively unchanged from 19 up to 100h of milling (20-30 nm) and then drastically decreases reaching a saturation size of about 3 nm after 200 h of milling. Lattice strains are on the average less than 1%. Simultaneously, the ordered L12 crystal structure undergoes disordering which commences after approximately 40h and terminates after 160h of milling. The microstructure of powder particles undergoes a complex evolution.With increasing milling time the particles are formed which appear to contain a work-hardened core. Each such a particle is surrounded by a heavily deformed, hard outer layer containing nanometer grains. After 386 h of milling all the core/outer layer particles are transformed into uniform 'no core' ones, characterized by approximately 3 nm crystallite size (XRD measurements). The microhardness data for both outer layer in the powder particles with a core, and the 'no core' particles can be fitted by a Hall-Petch dependence on the inverse root of crystallite size: HV 0·01 = 431·7 + 387·5d-0·5 (kg mm-2) where HV 0·01 is Vickers microhardness at 0·01 kg and d is crystallite size in nm. These results are discussed in view of the existing models of hardening of nanosized materials. © 1998 Elsevier Science Limited. All rights reserved.

Publication Date


  • 1998

Citation


  • Varin, R. A., Wexler, D., Calka, A., & Zbroniec, L. (1998). Formation of nanocrystalline cubic (L12) titanium trialuminide by controlled ball milling. Intermetallics, 6(6), 547-557. doi:10.1016/S0966-9795(98)00006-5

Scopus Eid


  • 2-s2.0-0032156229

Start Page


  • 547

End Page


  • 557

Volume


  • 6

Issue


  • 6

Abstract


  • Pre-alloyed, as-cast ingots of the Mn-modified, cubic (L12) titanium trialuminide (65at% Al, 25·6at% Ti and 9·4at% Mn) were homogenized (1000deg;C/100), crushed into a coarse-particle powdered material and subsequently ball milled for up to 386h under shearing mode in a controlled ball movement mill. X-ray spectra of milled powders showed line broadening and decrease in intensity of Bragg peaks with increasing milling time. This is associated with the formation of nanocrystalline grains and lattice strains upon milling. Crystallite size calculated from peak broadening, remains relatively unchanged from 19 up to 100h of milling (20-30 nm) and then drastically decreases reaching a saturation size of about 3 nm after 200 h of milling. Lattice strains are on the average less than 1%. Simultaneously, the ordered L12 crystal structure undergoes disordering which commences after approximately 40h and terminates after 160h of milling. The microstructure of powder particles undergoes a complex evolution.With increasing milling time the particles are formed which appear to contain a work-hardened core. Each such a particle is surrounded by a heavily deformed, hard outer layer containing nanometer grains. After 386 h of milling all the core/outer layer particles are transformed into uniform 'no core' ones, characterized by approximately 3 nm crystallite size (XRD measurements). The microhardness data for both outer layer in the powder particles with a core, and the 'no core' particles can be fitted by a Hall-Petch dependence on the inverse root of crystallite size: HV 0·01 = 431·7 + 387·5d-0·5 (kg mm-2) where HV 0·01 is Vickers microhardness at 0·01 kg and d is crystallite size in nm. These results are discussed in view of the existing models of hardening of nanosized materials. © 1998 Elsevier Science Limited. All rights reserved.

Publication Date


  • 1998

Citation


  • Varin, R. A., Wexler, D., Calka, A., & Zbroniec, L. (1998). Formation of nanocrystalline cubic (L12) titanium trialuminide by controlled ball milling. Intermetallics, 6(6), 547-557. doi:10.1016/S0966-9795(98)00006-5

Scopus Eid


  • 2-s2.0-0032156229

Start Page


  • 547

End Page


  • 557

Volume


  • 6

Issue


  • 6