Materials Research Letters

Wang, Lingfeng; Li, Yinghong; Zhou, Liucheng; Lou, Yanshan; Liu, Shijie; Zheng, Dayong; Yi, Min

doi: 10.1080/21663831.2023.2275599pmid: N/A

The aviation industry is a key market that promote additive manufacturing (AM) technology since there are huge demands for precision manufacture of high-value complex structural parts and repair of local defects. Extensive research has been conducted on AM process, characterization, and fatigue evaluation of titanium alloy, but there are rare comprehensive reviews on fatigue evaluation methods used for AM aero-engine blades. Rigorous tests, evaluation, and certification are necessary before AM technology is applied in aero-engine blade repair, although it has shown great advantages in different engineering fields. This paper introduces the application of AM technology in the manufacturing and repair of aero-engine titanium alloy blades, summarizes the key factors affecting the fatigue performance of AM titanium alloys, thoroughly discusses the fatigue mechanism, research methods, and process optimizations of AM parts, and compares the differences among several prediction models in fatigue evaluation of AM titanium alloys. Abbreviations: FOD: foreign object damage; LCF: low cycle fatigue; HCF: high cycle fatigue; LSP: laser shock peening; SP: shot peening; LP: low-pressure; HAZ: heat affected zone; AM: additive manufacturing; LAM: laser additive manufacturing; DED: directed energy deposition; PBF: powder bed fusion; LPBF: laser powder bed fusion; EPBF: electron beam powder bed fusion; LMD: laser metal deposition; LCD: laser cladding deposition; LENS: laser engineered net shaping; SLM: selective laser melting; EBM: electron beam melting; SEBM: selective electron beam melting; SLS: selective laser sintering; DMLS: direct Metal Laser Sintering; DMD-L: direct metal deposition by laser; DMD-P: direct metal deposition by plasma arc; LS: laser sintering; AB: as-built; LOF: lack of fusion; EVS: extreme value statistics; LEVD: largest extreme value distribution; VED: volumetric energy density; PD: probabilistic distribution; MRO: maintenance, repair & operations; STA: solution treatment & aging; BUS: broken-up structure; HIP: hot isostatic pressing; M&P: machining and polishing; SR: stress relief; AN: annealing; DAN: double annealing; PBG: prior β grain; TCT: thermochemical treatment; AC: air cooling; SMAT: surface mechanical attrition treatment; CT: computer tomography; SEM: scanning electron microscope; FCG: fatigue crack propagation; FCGR: fatigue crack propagation rate; SIF: stress intensity factor; EIFS: equivalent initial defect size; LEFM: linear elastic fracture mechanics; ML: machine learning; ANN: artificial neural network; FNN: feed forward neural network; CNN: convolutional neural network; PINN: physics-informed neural network; PPgNN: probabilistic physics-guided neural network; ANFS: adaptive network-based fuzzy system; SVM: support vector machine; SVR: support vector regression; RF: random forest; CDM: continuum damage mechanics. IMPACT STATEMENT The fatigue performance of additively manufactured titanium alloys is influenced by a combination of microstructure, defects, surface roughness, and residual stresses. In the context of fatigue assessment, the role of defects is typically prioritized.

Gao, Zhenhuan; Zhang, Peng; Li, Jiao; Gong, Xiufang; Yuan, Yong; Song, Xiaolong

doi: 10.1080/21663831.2023.2276340pmid: N/A

We investigate the tensile deformation behavior and mechanism of nickel-based superalloy CM247LC, which has been subjected to various ageing treatment schemes, but possesses almost the same γ′ particle size, at 600°C. It is found that the transition in the deformation mode from particle shearing plus microtwinning to particle shearing accounts for the decrease in the work-hardening rate and tensile strength with ageing temperature. Our study provides a new strategy to design the heat treatment schedule to achieve a good compromise between the strength and plasticity for superalloys by tunning the operative deformation and fracture mechanisms.

Voigt, Hendrik; Rigoni, Aaron; Boltynjuk, Evgeniy; Rösner, Harald; Hahn, Horst; Wilde, Gerhard

doi: 10.1080/21663831.2023.2278597pmid: N/A

Crystallization processes of glass-glass interfaces in sputtered CuZr thin film nanoglasses were directly studied using in situ heating experiments in a transmission electron microscope (TEM). By combining the in situ technique with a sophisticated symmetry analysis based on nanobeam diffraction patterns (NBDP) and electron correlation microscopy (ECM) to capture the relaxation dynamics in the nanoglass, correlations between excess volume and nucleation kinetics are attained on a microscopic scale. Particularly, glass-glass interfaces with their increased excess volume promote the onset of crystal nucleation.

Zhou, Gang; Yang, Yan; Luo, Yangyang; Li, Qian; Luo, Qun; Zhang, Yu; Jiang, Bin; Peng, Xiaodong; Pan, Fusheng

doi: 10.1080/21663831.2023.2278589pmid: N/A

A Mg-6Li-3Al-1Sn (LAT631) alloy with a bimodal-grained structure was prepared via hot extrusion, followed by room temperature rotary swaging (RTRS). The as-extruded LAT631 alloy undergoes dynamical recrystallization, and massive twins are introduced during RTRS. Especially, Al segregation is generated with massive Al solutes surrounding Sn-rich particles via RTRS. Introducing twins and Al-rich segregation are critical factors for enhancing strength, and the increased proportion of DRXed grains is beneficial to improving the elongation in RSed alloy. This research demonstrates that strategic control of recrystallization and segregation by rotary swaging provides an innovative approach to optimizing the mechanical properties of Mg-Li alloys.

Ma, Yan; Qiu, Keliang; Xu, Ning; Yang, Chengpeng; Zhang, Jiabao; Zhang, Zihao; Deng, Qingsong; Yue, Yonghai; Wang, Lihua; Han, Xiaodong

doi: 10.1080/21663831.2023.2275600pmid: N/A

The deformation of a single-crystal Fe48Mn32Co10Cr10 alloy is captured in situ at the atomic scale. The results show that full and partial dislocations, along with deformation twins, are involved in the deformation process. Partial dislocation activities result in the formation of nanotwins, high-density coherent twin boundaries, and incoherent twin boundaries. Full dislocations interact with the coherent/incoherent twin boundaries, and partial dislocations, thereby producing high strength and remarkable strain hardening. The observed high activity of full dislocations can be attributed to the inhomogeneous distribution of solid solution atoms in the alloy.

Alvarez, Gustavo A.; Casamento, Joseph; van Deurzen, Len; Khan, Md Irfan; Khan, Kamruzzaman; Jeong, Eugene; Ahmadi, Elaheh; Xing, Huili Grace; Jena, Debdeep; Tian, Zhiting

doi: 10.1080/21663831.2023.2279667pmid: N/A

Aluminum scandium nitride (AlScN) has been receiving increasing interest for radio frequency microelectromechanical systems because of their higher achievable bandwidths owing to the larger piezoelectric response of AlScN compared to AlN. However, alloying scandium (Sc) with aluminum nitride (AlN) significantly lowers the thermal conductivity of AlScN due to phonon alloy scattering. Self-heating in AlScN devices potentially limits power handling, constrains the maximum transmission rate, and ultimately leads to thermal failure. We grew plasma-assisted molecular beam epitaxy (PAMBE) AlScN on AlN-Al2O3 and GaN-Al2O3 substrates, and compared the cross-plane thermal conductivity to current work on AlScN grown on Si substrates.

Stewart, James A.; Startt, Jacob K.; Dingreville, Remi

doi: 10.1080/21663831.2023.2280635pmid: N/A

Through atomistic simulations, we uncover the dynamic properties of the Cantor alloy under shock-loading conditions and characterize its equation-of-state over a wide range of densities and pressures along with spall strength at ultra-high strain rates. Simulation results reveal the role of local phase transformations during the development of the shock wave on the alloy's high spall strength. The simulated shock Hugoniot results are in remarkable agreement with experimental data, validating the predictability of the model. These mechanistic insights along with the quantification of dynamical properties can drive further advancements in various applications of this class of alloys under extreme environments.

Willenshofer, P. D.; Tunes, M. A.; Kainz, C.; Renk, O.; Kremmer, T. M.; Gneiger, S.; Uggowitzer, P. J.; Pogatscher, S.

doi: 10.1080/21663831.2023.2281589pmid: N/A

Crossover aluminium alloys have recently been introduced as a new class of coarse-grained age-hardenable alloys. Here, we study the evolution of precipitation of the T-phase — $ {\rm Mg}_{32}({\rm Zn},{\rm Al})_{49} $ M g 32 ( Z n , A l ) 49 -phase — in a 5xxx/7xxx crossover alloy with coarse- and ultrafined microstructures. Both alloys were examined using differential scanning calorimetry, X-ray diffraction and in situ transmission electron microscopy. The ultrafine-grained alloy revealed significant different and accelerated precipitation behaviour due to grain boundaries acting as fast diffusion paths. Additionally, the ultrafine-grained alloy revealed high resistance to grain growth upon heating, an effect primarily attributed to inter-granular precipitation synergistically with trans-granular precipitation of T-phase.