Metal‐Matrix Materials for High‐Temperature Applications with Liquid Aluminum

Abstract

Herein, powder metallurgically processed transformation‐induced plasticity effect (TRIP)‐steel‐matrix composites with additions of TiO2 or Al2O3–TiO2 are investigated for their potentional use as a impact pad in aluminum melting furnaces. The composites contain volume fractions of 10% or 30% ceramic particles dispersed in a CrMnNi‐steel matrix. The formation of ceramic precipitates in the steel and the interactions between the matrix and the ceramic particles during sintering influence the microstructure of the fired materials. TiO2 promotes the formation of Mn–Ti–O spinel‐type structures whereas the Al2O3–TiO2 material induces the additional formation of Ti–Mn–Al–O solid solutions but reduces the densification progress. Despite material changes, the steel matrix undergoes α'‐martensite formation during quasi‐static tensile loading at room temperature in the reference material and in the composite variants. The yield strength in the composite variant with 10 vol% TiO2 increases by 28% (constant with 10 vol% Al2O3–TiO2), whereby the ultimate tensile strength and the fracture strain are lower for all composite variants as compared to the pure steel. The yield strength of the materials after immersion test in liquid aluminum at 800 °C is +80% (10% TiO2) or +29% (10% Al2O3–TiO2) as compared to the corroded steel material.

Powder Metallurgical Processing of MMC Pressure Springs Based on Zirconia and TRIP Steel

“…Due to the distribution of Fe, Cr, and Ni, two different phases have been detected. Segregation of chromium was observed as described by Weigelt et al [24] In this contribution, a chromium-enriched, single-crystalline phase and a chromiumdepleted, fine-crystalline phase were found. The chromium-rich phase had very good diffraction patterns and was indicated as δ-ferrite.…”

“…[14] Especially manganese and magnesium tend to diffuse from the steel matrix into the ceramic particles forming mutual phases. [24] The steel matrix, shown in Figure 5 and 6, is not uniform. Due to the distribution of Fe, Cr, and Ni, two different phases have been detected.…”

“…The formation of α 0 -martensite during compressive load testing was determined with the aid of M-SAT measurement where an increase in ferromagnetic phase of 4.5 vol% was determined in sintered state. The effect of zirconia particle reinforcement in transformation induced plasticity (TRIP) steels has been intensively investigated by Martin et al, [23] Ehinger et al, [28] and Weigelt et al [24] The phase transformation of austenite to α 0 -martensite is caused by plastic deformation of the austenite (dislocation movement, formation of stacking faults, generation of deformation bands and their intersections). Due to the incorporation of ceramic particles such as zirconia, the plastic flow is constricted.…”

Evaluation of Critical Parameters for the Fabrication of Metal Hollow Spheres Using an Alginate‐Based Sol–Gel Process

“…Segregations of chromium as described by other researchers were not detected. [ 20,21 ] A formation of carbide precipitates was not registered even though the residual carbon concentration after debinding was determined to be 0.1 wt%, which was higher as compared to the initial steel powder.…”

Corrosion-Resistant Steel–MgO Composites as Refractory Materials for Molten Aluminum Alloys

“…Steel–ceramic composites benefit from the synergy between the steel and the refractory ceramics, and are characterized by good machinability, higher ductility, and advantageous thermomechanical properties, leading to better thermal shock resistance. The addition of ceramics to the steel can increase the corrosion resistance against molten aluminum alloy [ 35 ]. Furthermore, multiple studies in the field of steel–ceramic composites present their ability to be produced in a made-to-order fashion [ 36 , 37 , 38 ].…”