High strength nanocrystalline L12-Al3(Ti,Zr) intermetallic synthesized by mechanical alloying

Microstructure-hardness relationship of Al–(L12)Al3Ti nanocomposites prepared by rapid solidification processing

“…However, superlattice reflections of L1 2 -Al 3 Ti, viz., (100) and (110) were not found. The reason for the absence of superlattice reflection of L1 2 -Al 3 Ti phase forming in Al-Ti alloys is the small difference in the atomic scattering factors of Al and Ti as reported earlier [12,13,21]. These results indicate that rapidly solidified Al-Ti alloys form both equilibrium (DO 22 ) as well as metastable (L1 2 ) Al 3 Ti intermetallic in a-Al matrix.…”

“…It is well known that non-equilibrium processing routes, viz., RSP and MA, extend the solid solubility in any metallic system. In Al-Ti alloys, Ti is known to decrease the lattice parameter of Al being small in atomic radius compared to Al [12,13,21,22]. 1 at.% Ti decreases the lattice parameter of Al (0.405 nm) by 0.001 nm [22].…”

Al–(L12)Al3Ti nanocomposites prepared by mechanical alloying: Synthesis and mechanical properties

“…4). It may be noted here that the no superlattice reflection of L1 2 -Al 3 Ti was observed in the asmilled condition in binary Al 75 Ti 25 composition in our earlier work [21][22][23][24]. The (1 1 0) superlattice reflection observed in this study is attributed to annihilation of the defects which were introduced into the alloy powders during MA and the peak sharpening due to grain coarsening, both due to annealing.…”

“…The basic idea of fabricating the Al-based nanocomposites by MA lies in examining the stability of the metastable L1 2 -Al 3 Ti phase so as to maintain the Ni-based superalloy like microstructure both at room temperature, as well as, at elevated temperatures. Also, MA was adopted for the synthesis of nanocomposites because, (a) being a far-from-equilibrium process provides ample scope for easy formation of metastable phase like L1 2 structure [21][22][23][24], (b) involves severe plastic deformation to promote uniform mixing and refining of the constituent phases in the all materials, and (c) easy consolidation and subsequent annealing for good densification, as reported recently by the present authors [23,24]. Table 1 illustrates the conditions of MA used and the compositions studied in the present work.…”

Microstructure and mechanical properties of bulk nanocrystalline Al88Mm5Ni5Fe2 alloy consolidated at high pressure

“…In fact, it was clearly shown in this work that a change of density in amorphous samples strongly affects the microhardness and therefore special attention might be devoted to enhance the quality of compaction of the consolidated powder to optimise the hardness of the system. Recently, very high values of hardness (>900HV ¼ 8.83 GPa) have been reported for nanocrystalline intermetallic (AlCu) 3 Zr and (AlMn) 3 Zr after consolidation in pore free bulk samples by spark plasma sintering [20] whereas less compact samples (77% of density) of similar alloys exhibit only values < 350HV ¼ 3.43 GPa) [21].…”