Spark Plasma Sintering of a Zr‐Based Metallic Glass

Abstract

Amorphous metallic alloys are among the most recent class of metallic materials. [1][2][3] Indeed, low glass forming ability (GFA) of major alloys induces manufacturing into thin ribbons shape (thickness < 100 mm) since the 1960s. The development of bulk parts with reasonable dimensions is more recent (early 1990s), and it still concerns small variety of alloys having high GFA. The formation of metallic glasses (MGs) is kinetically controlled and obeys empirical rules first stated by Inoue. [4] Many metals can be processed in MG form, such as Zr, Ti, Ni, or Fe, resulting in reasonable coverage domains of properties (mechanical, magnetic, resistance to corrosion, wear). [5][6][7] Amorphous alloys present neither long-range ordering nor structural defects and then do not experience homogenous distribution of defects for strain accommodation, like in crystalline alloys. In contrast, it follows that MG possess high strength close to the theoretical s max % E/20, no macroscopic ductility and high resilience owing to a moderate Young's modulus (similar to those of their crystalline counterparts) and an average 2% elastic deformation.Bulk MGs are essentially manufactured using casting and rapid quenching techniques, thus limiting shapes and dimensions of the available parts. [8] One promising way consists in manufacturing bulk parts from fine amorphous powders, even having a low GFA. [9] Atomization of MG powders have been studied since the early 1980s, [10] and attempts for sintering were carried out by extrusion, [11] hot pressing, [12] and more recently spark plasma sintering (SPS). [13][14][15][16][17][18][19] This paper reports on an analysis of SPS consolidation of a Zr 57 Cu 20 Al 10 Ni 8 Ti 5 MG produced by high-pressure gas atomization. This MG was extensively studied in its bulk form for its structure, thermal, and mechanical behavior and is then the relevant reference for comparison with sintered parts. [20,21] Systematic thermal and structural analyses of SPS consolidated powders with various grain sizes have been performed to identify specific SPS densification and consolidation mechanisms. Moreover, local transmission electron microscopy (TEM) analyses of the specimens point out occurrence, with clear evidences, of some physical events not observable in crystalline solids, as for example temperature overshoot revealed by partial devitrification. This study aims to approach the specific mechanisms of sintering through SPS of MGs, with particular interest in phenomena localized at the particle contacts (necks).

A Novel Approach to Develop Chalcogenide Glasses and Glass-Ceramics by Pulsed Current Electrical Sintering (PCES)

“…These amorphous materials are most often obtained by mechanical alloying, melt-spinning or atomization. Recently, Nowak et al (Nowak et al, 2011) and Perriere et al (Perriere et al, 2011) studied the phenomenon during SPS treatment at the origin of the microstructure and densification of glasses. The devitrification in metallic glasses during SPS treatment has also been studied in order to obtain composite materials or glass-ceramics (Li et al, 2010).…”

“…This suggests that the first mechanism described above, i.e achieving full density prior to any significant crystallization should be favored. However, in the specific case of metallic glasses, it is reported that concurrent mechanisms are involved during SPS treatment (Perriere et al, 2011).…”

Investigation of the Mechanisms Involved in the Sintering of Chalcogenide Glasses and the Preparation of Glass‐Ceramics by Spark Plasma Sintering

“…This is confirmed by Perriere et al . who suggest that: considering an equivalent electrical outline of the SPS apparatus.…”

Reactive Spark Plasma Sintering: Successes and Challenges of Nanomaterial Synthesis

“…From the reported experimental results, it can be assumed that the fine-grained structure of the composite was due to a sequence of several solid state reactions occurring in the reactant mixture. Flexible control over the SPS parameters allows inducing nanocrystallization of amorphous metallic [34,35] and nonmetallic [36] matrices and maintaining the nanostructure of the composite materials until the end of sintering. A further If refractory compounds are synthesized in the SPS form by exothermic chemical reactions, local heat evolution in the reaction initiation zones and the concomitant temperature rise in the adjacent regions can make it very challenging to synthesize materials with nanosized grains.…”