Temperature-responsive hydrogel for tumor embolization therapy

Rapid heating and solidification rates involved in additive manufacturing result in non-homogenous mi-crostructural features, microsegregation and residual stresses, leading to deteriorated mechanical proper-ties. Although the rather new Ti-5553 (Ti-5Al-5Mo-5V-3Cr) metastable beta-Ti alloy is printable by laser powder-bed fusion (LPBF), it exhibits poor mechanical strength compared to conventionally forged com-ponents due to the lack of second phase strengthening in the as-printed state. Therefore, post-processing heat treatment is essential to enhance the mechanical properties of the printed parts. In this research work, LPBF-made Ti-5553 specimens were subjected to varying heat treatment cycles to modify their corre-sponding microstructure in terms of the morphology and distribution of alpha particles. Differential Scanning Calorimetry (DSC), X-Ray diffraction (XRD) patterns, and electron backscatter diffraction (EBSD) results suggest that solutionizing at the upper alpha + beta region (800 degrees C) offers a good combination of finer grain size and satisfactory alpha dissolution. On aging in the range of 500 - 700 degrees C for 0.5 - 4 h, growth of alpha particles with different morphologies was observed. A combination of multiple alpha morphologies, including Widmanstatten, lenticular, cylindrical and lamellar was identified based on the heat treatment conditions. Consequently, a wide range of microhardness from 300 to 500 HV was observed due to phase transformations in the mi-crostructure, which control the mechanical properties. The subsequent tensile tests validated the improved mechanical properties further as the tensile strength increased from 780 +/- 10-1640 +/- 6.29 MPa, compared to the as-printed specimens. Examination of the fracture surfaces revealed intergranular failure following aging at 500 degrees C due to segregation of alpha particles at grain boundaries. At 600 degrees C, the fracture was initially intergranular, which slowly transformed to a ductile fracture with time. At 700 degrees C, the fracture was mainly ductile irrespective of the aging duration. (c) 2022 Elsevier B.V. All rights reserved.