Compression deformability of Γ and ζ Fe–Zn intermetallics to mitigate detachment of brittle intermetallic coating of galvannealed steels

Abstract

Micropillar compression tests made for each of the five intermetallic phases of the Fe-Zn system, which constitute the coating of galvannealed steels, have revealed that the Γ phase formed in direct contact with the steel substrate and the ζ phase formed on the outermost surface are ductile, sandwiching the other three brittle phases (Γ 1 , δ 1k and δ 1p). Compression deformability of these ductile phases is considered to mitigate the coating failure through sustaining ruptured fragments of the brittle phases during the forming process.

Fe-Zn intermetallic phases prepared by diffusion annealing and spark-plasma sintering

“…The results of the studies clearly prove that the G 1 phase is the hardest phase in the hot-dip galvanized coating. It has also been shown 6 that the compression strength and hardness decrease with the increasing hardness, hence, the d and G 1 phases are relatively fragile. Both d and G 1 phases do not experience plastic deformation after exceeding the yield stress; instead a brittle fracture occurs.…”

“…These layers provide a good protection against the corrosion and an increased resistance to wear because the intermetallic phases are harder than the h phase. 2 With respect to the mechanical properties of intermetallic phases, the microhardness and compressive strength 5,6 have mostly been analysed. According to single-crystal hardness studies, 7 the highest hardness is achieved by d and G 1 phases.…”

Effect of orientation and lamellar spacing of Fe2B on interfaces and corrosion behavior of Fe-B alloy in hot-dip galvanization

“…Dislocation lines 45 to the horizontal direction were parallel to each other, and the average distance between two dislocation lines was approximately 650 nm (Fig. 10b), which indicates that dislocations may be important for adhesion [34,35]. The SADP of z-FeZn 13 at the pinning interface indicates that slipping deformation occurred on the (110) plane of z-FeZn 13 (Fig.…”

Micropillar compression deformation of single crystals of Co3(Al,W) with the L12 structure

“…In recent years, however, a method based on compression testing of small pillars of single crystals of the order of micrometer size, which can be prepared from relatively small crystal grains in polycrystals by focused ion beam (FIB) machining, has been developed and opened a way to measure CRSS values of alloys even if large single crystals are unavailable [12][13][14][15][16]. It has been known that the CRSS values of single-crystal micropillars in fcc and body-centered cubic (bcc) metals decrease with the increase in pillar size, obeying an inverse power-law scaling [17][18][19][20].…”

“…Since the occurrence of yield stress anomaly in the constituent γ′ phase is important for the strength of γ + γ′ two-phase alloys at high temperatures, comparison of the strength of Co 3 (Al,W) with those with Ni 3 Al-based L1 2 compounds should be made to see how significantly Co 3 (Al,W) contributes to the strength of Co-based superalloys especially at high temperatures. However, the critical resolved shear stress (CRSS) has not been available for Co 3 (Al,W) due to the difficulties in preparing single crystals of the γ′-Co 3 (Al,W) single-phase large enough for the study of plastic deformation [11].In recent years, however, a method based on compression testing of small pillars of single crystals of the order of micrometer size, which can be prepared from relatively small crystal grains in polycrystals by focused ion beam (FIB) machining, has been developed and opened a way to measure CRSS values of alloys even if large single crystals are unavailable [12][13][14][15][16]. It has been known that the CRSS values of single-crystal micropillars in fcc and body-centered cubic (bcc) metals decrease with the increase in pillar size, obeying an inverse power-law scaling [17][18][19][20].…”