Towards an alloy design strategy by tuning liquid local ordering: What solidification of an Al-alloy designed for laser powder bed fusion teaches us

Ageing response and strengthening mechanisms in a new Al-Mn-Ni-Cu-Zr alloy designed for laser powder bed fusion

“…Six phases have been identified in the SR sample, five of them being Al-based intermetallics, which agrees with our previous study in which their presence had been confirmed using nanodiffraction in the TEM, see [39]. Two of the intermetallic phases have a complex structure, namely the Al9Ni2 phase (monoclinic) and the Al60Mn11Ni4 phase (orthorhombic).…”

“…Two forms of the Al3Zr phase were identified by XRD: the cubic L12 metastable form found in the SR, SR+400°C/1h, and SR+400°C/4h samples; and the stable D023 form only found in the SR+400°C/96h sample. In the SR conditions, the presence of the metastable L12 form is associated with the presence of primary L12-Al3Zr particles located at the grain center in the FEZ and showing a cubic shape morphology as already shown in [34,39,40]. An example of such a primary L12-Al3Zr precipitate was found in the APT sample shown in Figure 7a.…”

“…Since APT is a very local characterization technique, it is possible that the specimens were extracted from a region located in the bottom region of a CZ. Second, it has been shown that icosahedral short range order (ISRO) in the liquid during melt pool affects the solidification of this material [39,40]. In particular, the presence of ISRO in the liquid slows down the diffusivity of solutes due to a cage effect, see e.g.…”

Direct Ageing of LPBF Al-1Fe-1Zr for High Conductivity and Mechanical Performance

“…This technique is presented in detail in [33] and has been applied successfully to LPBF microstructures, see e.g. [34][35][36][37]. The quasi-parallel electron beam with a spot size of about 1 nm on the TEM lamella was scanned over a region of interest.…”

Nucleation Burst in Additively Manufactured Inconel 718: 3d Characterization of Isro - Induced Equiaxed Microstructure

“…The Laves phase is detrimental to mechanical properties and is usually dissolved by post heat treatment during the homogenisation step [21,22]. The rapid melting and solidification conditions in AM can induce strong out-of-equilibrium solidification conditions that could induce ISRO through undercooling effects [23] and further promote not only Laves phase but also other metastable phase formations that could act as nucleating agents and induce twinning grain boundaries in the fcc phase [24].…”