On the Characterization of a Hitherto Unreported Icosahedral Quasicrystal Phase in Additively Manufactured Aluminum Alloy AA7075

Abstract

Aluminium alloy AA7075 (Al-Zn-Mg-Cu) specimens were prepared using selective laser melting, also known as powder bed fusion additive manufacturing. In the as-manufactured state, which represents a locally rapidly solidified condition, the prevalence of a previously unreported icosahedral quasicrystal with 5-fold symmetry was observed. The icosahedral quasicrystal, which has been termed -phase (nu-phase), was comprised of Zn, Cu and Mg.

Corrosion of Additively Manufactured Alloys: A Review

“…Herein, only the key variables reported in the literature are covered (Table 2). 61,64,[73][74][75][76][77][78][79][80][81][82][83][84][85] Several researchers have, often with little to no experimental support, reported that porosity may significantly impact the pitting characteristics of alloys produced by AM. 61,[73][74][75][76][77] However, a mechanistic description of how pores (particularly unconnected pores) may assist in pit initiation/propagation is yet to be clarified.…”

Microstructure and corrosion evolution of additively manufactured aluminium alloy AA7075 as a function of ageing

“…The AA7075 powder, with size distribution of 20-63 µm, was supplied by LPW technology. A Concept Laser Mlab cusing-R was used for SLM, described in detail in [13], with the production conditions for specimens tested herein consisting of; laser power, 95 W; laser scan speed, 200 mm/s; and layer thickness, 25 µm. In addition to SLM prepared specimens, wrought AA7075-T6 rod was also studied for comparison.…”

“…The mechanism of such nucleation processes is complex, considering high cooling rates and subsequently negligible solute diffusion rates during the SLM process [1][2][3][4][5][6][7]59]. However, most of the particles in as-SLMed AA7075 were characterised to be of icosahedral quasicrystalline phase (Figure 3c), termed as -phase (Mg-Zn-Cu(-Al)) [13]. As a result of coexistence of different phase particles at a single position, the determination of accurate composition of such particles is challenging.…”

“…To date, studies on the microstructure and mechanical properties of SLMed 7xxx Alalloys are limited [6,[13][14][15][16][17][18], and in the context of corrosion, no prior studies exist to date. A recent study discovered the predominant presence of a nanometre scale icosahedral quasicrystalline particle, termed -phase [13]. This () phase was comprised of Zn-Mg-Cu(-Al), a structurally and chemically unique in the Al-matrix of as-SLMed AA7075 [13].…”

“…A recent study discovered the predominant presence of a nanometre scale icosahedral quasicrystalline particle, termed -phase [13]. This () phase was comprised of Zn-Mg-Cu(-Al), a structurally and chemically unique in the Al-matrix of as-SLMed AA7075 [13]. As a consequence of this discovery, a more detailed study upon as-SLMed AA7075, including as a function of artificial ageing, is essential in the context of understanding microstructural evolutionand also the corrosion response in contrast to wrought AA7075-T6.…”