Characterization of Graphite Crystal Structure and Growth Mechanisms Using FIB and 3D Image Analysis

Abstract

Considering the significant influence of the morphology of graphite inclusions on the properties of cast iron it is important to understand the correlation between manufacturing parameters and resulting microstructure. In particular, understanding the effect of alloying elements and inoculants on the formation and growth mechanisms of the graphite particles provides the basis for exact tailoring of the microstructure and thus exact tailoring of effective properties of cast iron. Experimental observations of the three‐dimensional (3D) structure of graphite particles, high resolution chemical analysis of nuclei and other inclusions, as well as quantitative characterization of possible growth mechanisms have confirmed certain existing theoretical models for nodular and flake graphite and provided a comprehensive description of all intermediate morphologies. Precise analysis of the graphite's crystal structure based on target preparation of transmission electron microscope thin foils opens additional possibilities for estimating of the properties of different graphite types.

On the nucleation of graphene by chemical vapor deposition

“…This is probably because that the triangular Cu(111) plane is prone to have more similarities in crystallographic geometry as the hexagonal graphene lattice than other crystal planes, thus reducing the nucleation barrier, since the lattice mismatch between graphene and underlying metal will cause an additional energy cost (E is increased). 29,32 This result is also supported by the previous report that the additional energy cost due to the lattice mismatch can result in the destabilization of graphene nuclei. 29 Although there has been some concern that graphene may preferentially nucleate and grow on specific Cu crystallographic surfaces, 33 our results provide the first CVD-derived experimental evidence.…”

Heterogeneous Nucleation of Graphite on Rare Earth Compounds during Solidification of Cast Iron

“…[1][2][3][4][5][6][7][8] Considering that nodularizing treatment is a series of processes involving the dissolution/melting of nodularizing agent, followed by reactions with solutes (S, O etc.) to form inclusions and,…”

“…In investigating the formation mechanism of nodular graphite, numerous studies have since identified the presence of these inclusions at the center of nodular graphite. [6][7][8] Hence, it is ascertained that non-metallic inclusions of REEs could serve as effective heterogeneous sites for graphite nucleation. In studying the effects of non-metallic compounds on the nucleation of graphite in cast iron, Ueda et al experimentally determined that compounds with low interfacial energy with the nucleated solids showed a stronger nucleating efficiency and, the interfacial energy between two solids were affected by crystallographic mismatch.…”

Microstructural model for the time‐dependent thermomechanical analysis of cast irons

“…This anisotropy is related to graphite's layered structure with strong covalent bonds within the basal planes and weak van der Waals bonds between them, which makes graphite a transversely isotropic material (Figure 1.c) [2,5,[45][46][47][48][49]. This anisotropy is related to graphite's layered structure with strong covalent bonds within the basal planes and weak van der Waals bonds between them, which makes graphite a transversely isotropic material (Figure 1.c) [2,5,[45][46][47][48][49].…”

“…This leads to particles in which some parts resemble the graphite crystalline structure of nodular graphite, while in other parts it resembles the crystalline structure of lamellar graphite [2,45,46,49]. This leads to particles in which some parts resemble the graphite crystalline structure of nodular graphite, while in other parts it resembles the crystalline structure of lamellar graphite [2,45,46,49].…”