Laser power modulated microstructure evolution, phase transformation and mechanical properties in NiTi fabricated by laser powder bed fusion

Chen, Wenliang; Yang, Qin; Huang, Shuke; Huang, Shiyang; Kruzic, Jamie J.; Li, Xiao Peng

doi:10.1016/j.jallcom.2020.157959

Cited by 46 publications

(20 citation statements)

References 49 publications

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“…3, MPEA feedstock with high oxygen content could result in high level of porosity in the fabricated MPEA parts, which is mainly attributed to the balling effects and the formation of oxides during solidification [160,161]. Moreover, due to the different evaporation rates of elements in MPEAs, the high temperature, and repeated melting and remelting process during AM can also lead to a compositional variation compared with the original powder, in particular when one the principal elements has a low boiling/evaporation point [157,162]. This will not only affect the microstructure and properties of the fabricated MPEAs but also influence the certification and qualification of MPEAs parts if demanding industrial applications, such as aerospace, are targeted.…”

Section: Control Of Processing Defects During Am Of Mpeasmentioning

confidence: 99%

Review: Multi-principal element alloys by additive manufacturing

Ferry

Kruzic

et al. 2022

J Mater Sci

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Multi-principal element alloys (MPEAs) have attracted rapidly growing attention from both research institutions and industry due to their unique microstructures and outstanding physical and chemical properties. However, the fabrication of MPEAs with desired microstructures and properties using conventional manufacturing techniques (e.g., casting) is still challenging. With the recent emergence of additive manufacturing (AM) techniques, the fabrication of MPEAs with locally tailorable microstructures and excellent mechanical properties has become possible. Therefore, it is of paramount importance to understand the key aspects of the AM processes that influence the microstructural features of AM fabricated MPEAs including porosity, anisotropy, and heterogeneity, as well as the corresponding impact on the properties. As such, this review will first present the state-of-the-art in existing AM techniques to process MPEAs. This is followed by a discussion of the microstructural features, mechanisms of microstructural evolution, and the mechanical properties of the AM fabricated MPEAs. Finally, the current challenges and future research directions are summarized with the aim to promote the further development and implementation of AM for processing MPEAs for future industrial applications.

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Section: Control Of Processing Defects During Am Of Mpeasmentioning

confidence: 99%

Review: Multi-principal element alloys by additive manufacturing

Ferry

Kruzic

et al. 2022

J Mater Sci

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“…Characterisation studies of LPBF-produced BMGs have mainly focused on layer-level structural variations, such as crystallisation and/or chemical variations in the melt-pool and heat-affected zones (HAZs) or structural periodicity that occurs in the amorphous phase across the build layers [13,18,[23][24][25]. In contrast, characterisation studies of traditional crystalline alloys produced by LPBF have often revealed variations in the microstructure at different locations along the build height due to the different heat input and thermal histories that evolve as the build progresses [26][27][28]. However, little is known about variations that possibly occur along the build height of printed BMG pieces, with one report noting similar porosity levels at the top, middle, and bottom sections of a printed sample [7].…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

Advanced structural analysis of a laser additive manufactured Zr-based bulk metallic glass along the build height

et al. 2022

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Additive manufacturing of bulk metallic glasses (BMGs) has opened this material class to an exciting new range of potential applications, as bulk-scale, net-shaped amorphous components can be fabricated in a single step. However, there exists a critical need to understand the structural details of additive manufactured BMGs and how the glassy structure is linked to the mechanical properties. Here, we present a study of structure and property variations along the build height for a laser powder bed fusion (LPBF) processed Zr-based BMG with composition Zr59.3Cu28.8Nb1.5Al10.4 commercially termed AMZ4, using hardness testing, calorimetry, positron annihilation spectroscopy, synchrotron X-ray diffraction, and transmission electron microscopy. A lower hardness, more rejuvenated glassy structure was found at the bottom of the build compared to the middle region of the build, with the structure and properties of the top region between the two. Such differences could not be attributed to variability in chemical composition or crystallisation; rather, the softer bottom region was found to have a larger medium range order cluster size, attributed to heat dissipation into the build plate during processing, which gave faster cooling rates and less reheating compared to the steady-state middle of the build. However, at the top of the build less reheating occurs compared to the middle, leading to a somewhat softer and less relaxed state. Graphical abstract

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“…These developments promise greater flexibility for the fabrication of complex structures with minimal defects, allowing tunable shape memory effect and superelasticity. The relationship between the AM process parameters and the thermal and mechanical properties of fabricated NiTi alloys has been under systematic investigations in the past, including laser power [12][13][14], scanning speed [15][16][17][18], scanning strategy [19][20][21][22][23], hatching space [24][25][26], design strategy [27], and chamber oxygen level [28]. These process parameters will ultimately alter the width and position of the phase transformation peak and influence strain recoverability [29,30].…”

Section: Introductionmentioning

confidence: 99%