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Item type:Publication, Access status: with files , Microstructure refinement and bicontinuity formation by distributed internal melting at the Ni₃Sn₄ peritecticGuided by a current interest in processing schemes, such as liquid-metal dealloying, providing fine-scale bicontinuous metal microstructures, we investigate the microstructure evolution during the peritectic melting of Ni₃Sn₄. The product microstructure is an interconnected array of spherical clusters of crystallographically aligned Ni₃Sn₂ ligaments, interpenetrated by a contiguous liquid phase. When quenched to room temperature, the prevalent microstructure consists of two interpenetrating solid phases. Leaching the solidified Sn melt produces monolithic porous bodies of Ni₃Sn₂. The characteristic structure size can reach down to 2 μm, a microstructure refinement by almost 2 orders of magnitude as compared to the 150 μm grain size of the master alloy. Remarkably, a more severe refinement is achieved at higher annealing temperatures. Our experiments identify liquid-film migration as the controlling process, here concurrent with constitutional supercooling and cellular solidification. We argue that peritectic melting exemplifies a more general family of processes of distributed internal melting (DIM). These processes exploit the abundant nucleation of regions of melt, finely distributed throughout a parent microstructure, when the alloy is heated into a two-phase solid–liquid regime of its phase diagram. DIM provides a novel and versatile pathway to fine-scale bicontinuous microstructures.Publicationtype: Journal Article63 61 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Formation of bicontinuous structures through liquid film migration(2026); This thesis identifies liquid film migration as the main microstructure formation mechanism during distributed internal melting (DIM) processes of TiAg, Ni3Sn4 and Cu93In7. Under different nucleation and growth mechanisms, distinct micro-scale bicontinuous structures can be obtained after DIM and quenching. This study demonstrates DIM as a novel method of fabricating bicontinuous structures, and provides basis for identifying more suitable alloy systems.Publicationtype: Doctoral Thesis65 38 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , How peritectic melting forms bicontinuous microstructuresFine-scale porous or bicontinuous microstructures may be prepared by liquid-metal dealloying (LMD). Reverse peritectic reactions, and specifically the peritectic melting of TiAg, have been proposed as dealloying-like processes that produce quite similar microstructures but avoid the restrictions on sample size inherent in LMD. Here, studies of the microstructure evolution during peritectic melting of TiAg suggest a formation mechanism that is not LMD-like but rather relies on the migration of liquid films. The process starts with wetting of the TiAg grain boundaries by the alloy melt. Successively, both Ti and Ag continue to dissolve from one side of the wetted boundary, while β-Ti deposits on the opposite side and the liquid film sweeps the pristine TiAg crystal. TiAg-Ti interfaces with well-defined orientation relationship and with concentration gradients support this picture, as does the phase morphology in partially decomposed samples. The process generates a bicontinuous structure with a solid Ti skeleton, interpenetrated by the Ag-rich melt. The bicontinuity is conserved even after coarsening. Upon quenching, the Ti phase transforms to α-Ti. This study clarifies the mechanism of peritectic melting in TiAg, and it may provide a basis for identifying other alloy systems suitable for producing bicontinuous microstructures by that process.Publicationtype: Journal Article19 10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Bicontinuous microstructure formation through partial melting(2024-09-01); ; Liquid-metal dealloying generates porous metals or interpenetrating-phase composites. Particularly attractive is the use of the alloy's innate melt for activating dealloying throughout the bulk, even in extended sample geometries, during reverse peritectic melting. We explore if interpenetrating-phase microstructures may be observed more generally during partial melting of solid solutions with an extended temperature interval of solid-melt coexistence. Incomplete wetting of grain boundaries by the melt is then a prerequisite for a bicontinuous structure. For a Cu-In alloy, we show that special grain boundaries remain non-wetted and provide a load-bearing backbone in the partially molten alloy, and that the bicontinuous structure is preserved during quenching to room temperature. Samples with a contiguous porosity can be obtained by leaching the solidified melt. As extended melting intervals are ubiquitous in binary alloys, our observations provide for the innate-melt-enabled preparation of monolithic interpenetrating-phase composites or porous metals in an extended set of alloy systems.Publicationtype: Journal Article36 69