Nanoprecipitate characterisation in NiTi and aluminium alloys: A TEM-based overview.

Abstract

Nanoscale precipitates are central to the functional and mechanical performance of many advanced alloys, yet their characteristics and spatial distributions can be directly resolved only by electron microscopy. In this poster-style article, focused ion beam-prepared TEM lamellae are used to provide a microscopy-focused overview of nanoprecipitate populations in two representative precipitate-controlled systems: a Ni-rich NiTi shape memory alloy and a multicomponent Al-Ce-(Er,Sc,Zr) aluminium alloy. In the NiTi alloy, a short heat treatment at 560°C for 1 min produced a recovered, subgrained matrix containing lenticular Ni₄Ti₃ precipitates with nanoscale dimensions. Representative TEM observations show precipitates located within the matrix and near dislocation-rich regions and subgrain boundaries, suggesting a local spatial association with the deformation substructure. In the Al-Ce-(Er,Sc,Zr) alloy, TEM analysis of aged samples shows coarse Al₁₁Ce₃ intermetallic phases within an Al matrix containing fine nanoscale precipitates consistent with L1₂-Al₃(Er,Sc,Zr) type precipitates. Selected-area electron diffraction (SAED) confirms the ordered L1₂ structure through superlattice reflections. Together, these case studies illustrate how FIB-TEM workflows enable direct visualisation of precipitate morphology, coherency, and spatial distribution across distinct alloy systems.