Plastic deformation of single crystals of Pt₃Al with the L1₂structure

Abstract

The plastic deformation behaviour of single crystals of Pt 3 Al with the L1 2 structure having an off-stoichiometric composition of Pt-27at.%Al has been investigated in compression from 77 to 1073 K. The L1 2 structure is not stable below around 220 K, transforming into either D0c or D0c' structure. Slip occurs along <110> both on (001) and on (111) with slip on (001) being the primary slip system, which operates for most crystal orientations except for near [001], accompanied by a considerably lower CRSS (critical resolved shear stress).The CRSS tends to decrease gradually with increasing temperature for both slip in the temperature range where the L1 2 phase is stable, except for a moderate increase in CRSS observed above 673 K for slip on (001). Dislocations with b = [101] dissociate into two collinear superpartials with b = 1/2[101] separated by an APB on the corresponding slip plane for both slip on (001) and (111). For slip on (111), dislocations tend to align along their screw orientation at room temperature, suggesting the high Peierls stress for their motion. The possibility of showing the normal (large negative) temperature dependence of CRSS at low temperatures as well as the reason for the absence of the anomalous (positive) temperature dependence of CRSS for slip on (111) at high temperatures is discussed.

Deep Insights into Complicated Superdislocation Dissociation and Core Properties of Dislocation in L12‐Al3RE Compounds: A Comprehensive First‐Principles Study

“…For edge dislocation, the line orientation is along the y-axis, which is defined as P ¼ YðxÞ and Q ¼ ZðxÞ. [30] For a continuous displacement distribution, atomic misfit energy E A can be calculated by integrating the misfit energy density along the displacement path…”

“…[28] The relative magnitudes of the SISF and APB energies of {111} planes can characterize the SISF dissociation based on the following condition: [29] Interestingly, the APB-type dissociation can also exist in both Pt-27at%Al and Pt-29at%Al crystals due to high SISF energies. [30] The final rapid descent at high temperatures could be also explained in the light of both APB-and SISF-types of dislocation dissociations [31] The mechanical properties of metal materials depend on the superdislocation dissociation behavior in the L1 2 particles. Therefore, the inherent mechanics, such as the dissociation model and the core properties, are essential and crucial for investigating high-performance Al alloys.…”

“…For example, the Pt 3 Al with an off‐stoichiometric composition (Pt‐27at%Al) is predicted to exhibit the yield stress anomaly for slip on the {111} plane on the basis of the low value of the criterion, which is inconsistent with the result of the experiment. [ 30 ] Therefore, the detailed superdislocation dissociation mode is difficult to determine based on the GSFE information for the L1 2 structure, thus requiring further precise investigations.…”

First-principles investigation on hydrogen doping of PtAl2 alloy

“…According to the Pt-Al phase diagram, the correlation between microstructure and mechanical properties is studied by experimental and theoretical calculation. The Pt 3 Al with L1 2 structure exhibits excellent plastic deformation and slips appear on (0 0 1) plane [16]. The first-principles calculation shown that the calculated boundary energy of Pt 3 Al along (1 1 1) and (0 1 0) planes is about of 205 mJ/m 2 and 414 mJ/m 2 , respectively [17].…”

Theoretical study of the elastic and thermodynamic properties of Pt_{3}Al with the L1_{2} structure under high pressure

“…The tetragonal DO c structure is found to collapse to the cubic L1 2 structure. Norihiko et al have discussed the single crystals of Pt 3 Al with the L1 2 structure from 77 to 1073 K [9]. Gornostyrev et al have employed first-principles electronic structure and total energy calculations of the phase stability and dislocation properties of Pt 3 Al to reveal the origins of its yield stress low temperature anomaly (LTA) [10].…”