The invention belongs to the technical field of shape memory alloys and additive manufacturing, and discloses a NiTiHf high temperature shape memory alloy with two-way shape memory effect and a 4D printing method and application thereof. The 4D printing method includes alloy powder processing, model building and substrate preheating, and 4D printing forming. The present invention patent is based on the design concept of reducing thermal gradient and the environmental friendly concept of clean production. It adopts substrate preheating combined with low laser power and low scanning speed laser powder bed fusion technology or low preheating temperature electron beam powder bed fusion technology to improve the formed alloy. The lattice compatibility with the NiTi substrate reduces the residual stress of the formed sample, and produces no cracks, no obvious holes, density 99%, high phase transformation temperature, excellent tensile mechanical properties and two-way shape memory effect.

A method of fabricating, at least in part, an article from a precursor thereof, the method comprising: providing the precursor, wherein the precursor comprises a metal having a closed pore therein; and hot isostatic pressing, HIPing, the precursor at an Nth temperature of a set of temperatures, at an Nth pressure of a set of pressures and for an Nth duration of a set of durations, thereby fabricating, at least in part, the article; wherein HIPing the precursor comprises regulating the set of temperatures, the set of pressures and/or the set of durations to control, at least in part, a morphology of the closed pore.

A method of fabricating, at least in part, an article from a precursor thereof, the method comprising: providing the precursor, wherein the precursor comprises a metal having a closed pore therein; and hot isostatic pressing, HIPing, the precursor at an Nth temperature of a set of temperatures, at an Nth pressure of a set of pressures and for an Nth duration of a set of durations, thereby fabricating, at least in part, the article; wherein HIPing the precursor comprises regulating the set of temperatures, the set of pressures and/or the set of durations to control, at least in part, a morphology of the closed pore.

Disclosed is a specific Ni-base superalloy, preferably in powder form, comprising at least 7.00 to 24.00 wt.-% Cr, 5.00 to 20.00 wt.-% Co, 0.00 to 5.00 wt.-% Fe, 0.00 to 10.00 wt.-% W, 0.00 to 3.00 wt.-% Nb, 0.00 to 10.00 wt.-% Mo, 0.00 to 6.00 wt.-% Ti, 0.50 to 6.00 wt.-% Al, 0.00 to 9.00 wt.-% Ta, 0.00 to 0.20 wt.-% C, 0.00 to 0.20 wt.-% Zr, 0.00 to 2.00 wt.-% Hf, 0.00 to 0.50 Si wt.-% and 0.00 to 0.20 wt.-% B, wherein the balance is Ni and unavoidable impurities. Further disclosed are processes for the manufacture of such Ni-base superalloy powders, processes and devices for the manufacture of three-dimensional objects, three-dimensional objects prepared by such processes and devices and the use of such a Ni-base superalloy in powder form for minimizing and/or suppressing microcrack formation in a three-dimensional object and/or for providing improved ductility and rupture life in creep conditions.

The present invention belongs to the field of additive manufacturing technology, and discloses a 4D printing method capable of in-situ regulating functional properties of nickel-titanium (NiTi) alloys and the application thereof. The method comprises the following steps: subjecting NiTi alloy bars to atomization milling to obtain NiTi alloy powder with a particle size of 15-53 m, placing the NiTi alloy powder in a discharge plasma assisted ball mill for discharge treatment to promote the activation of powder activity, then adding nano-sized Ni powder with a particle size of 100-800 nm to obtain mixed powder, then continuing the discharge treatment to realize the metallurgical bonding between the NiTi alloy powder and the nano-sized Ni powder to obtain the modified powder, and finally using the additive manufacturing technology to prepare and form the modified powder into a functionalized NiTi alloy. The present invention achieves the metallurgical bonding between the nano-sized Ni powder and the large-sized spherical NiTi alloy powder by adding the nano-sized Ni powder in the process of discharge treatment, which is conducive to preparing a bulk alloy with uniform composition, structure and properties and the parts made therewith.