Work

Multiscale Analysis of Defect Structures in Single-Crystalline CMSX-4 Superalloys

Year: 2025

Type: article

Abstract: An analysis of defects creation in the vicinity of the selector-root connection plane in single-crystalline turbine blades made of CMSX-4 Ni-base superalloy was performed using several experimental methods. A coupling of scanning electron microscopy and X-ray diffraction topography allowed the visualization of dendritic arrays and surface defects in the root part of the blades. As a result, contrast inversions and areas where internal stresses occur were observed. The defects on a microscopic scale were characterized using positron annihilation lifetime spectroscopy and transmission electron microscopy. The registered positron lifetimes, above 0.5 ns, beyond the range characteristic for defects generally reported in metals and their alloys suggest the presence extremely large void type defects. Herein, we have identified large defects, ca. 2-5 nm in diameter, formed due to the contraction of fluid metal, captured in inter-dendritic regions during the liquid-to-solid transition. This work is a precursor to the almost untouched area of the discussion of lifetimes characteristic for positron bound states, called positronium (>0.5 ns) in relation to the morphology of void-type defects in single-crystalline superalloys.

Source: Materials

DOI: 10.3390/ma18081819

Authors: Robert Paszkowski, Sławomir Kołodziej, Mirosława Pawlyta, Beata Chrząszcz

Institutions: University of Silesia in Katowice, Silesian University of Technology, University of St Andrews

Language: English

Topic: High Temperature Alloys and Creep

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funder: Uniwersytet Śląski w Katowicach