Method for preparing a heterogeneous metal composite structure for medical implantation

A method for preparing a heterogeneous metal composite structure for medical implantation, comprising the steps of:

• step 1, preparing, based on a selective laser melting technique or a laser powder bed fusion technique, titanium alloy powder (7) into a porous skeleton (2) according to different printing strategies,
• step 2, filling magnesium after being melted into pores of the porous skeleton (2), and
• step 3, cooling a titanium-magnesium interpenetrating phase composite structure prepared in step 2 to room temperature, and covering a surface of the titanium-magnesium interpenetrating phase composite structure with a hydroxyapatite coating, wherein
• in step 1, the porous skeleton (2) has a lattice dot-array structure;
• the lattice dot-array structure is a body-centered cubic dot-array structure, a closed tetragonal beam-0 type structure or a closed arc beam-0 type structure;
• the body-centered dot-array structure is a hexahedron with eight vertices as key nodes, which are connected to each other to form external beams, and centers of the six faces serve as nodes of internal beams, and the internal beams are connected to and combined with the external beams to form a body-centered cubic structure;
• the closed tetragonal beam-0 type structure is based on a face-centered lattice to construct diagonal X-beams, middles of which are fixed using straight columns, and a base configuration is constructed by mirroring 2-3 times, joints between the diagonal X-beams are at the face centers of each plane, and the closed tetragonal beam-0 type structure is built by regulating a total horizontal length a and a vertical length b;
• the closed arc beam-0 type structure is based on a quadrilateral, with four sides cut with circular arcs, constructing arc beams for circular arrays to establish the closed arc beam-0 type structure, in which a horizontal arc diameter C1 and a vertical arc C2 are used as variable parameters to regulate the porosity of the closed arc beam-0 type structure;
• and
• by printing multiple lattice dot-array structures for different impact conditions and filling the same according to different stress regions of a pelvis, the closed arc beam-0 type structure is arranged in a sacral region;
• the body-centered cubic dot-array structure is arranged in an acetabular region;
• and the closed tetragonal beam-0 type structure is arranged in an iliac region, for connecting the sacral region and the acetabular region;
• wherein the different stress regions comprise the sacral region, the acetabular region, and the iliac region;
• the different impact conditions comprise a largest bearing capacity, a good vibration damping performance, and a stability in deformation and effectively transmitting loads;
• wherein in step 1, the porous skeleton (2) is prepared using the selective laser melting technique by a following specific method:
• purging, before printing, a material molding chamber of a selective laser melting device (6) with high-purity argon gas until oxygen content in the molding chamber is less than 0.1%, preheating a print substrate to 200° C., ensuring a dimensional accuracy for printing the porous skeleton (2), continuously printing the titanium alloy powder (7) with a median diameter of 35 μm in layers using the selective laser melting technique under the conditions of a laser power of 100 W, a laser scanning speed of 1200 mm/s, and a layer thickness of 30 μm;
• wherein in step 1, a specific method for preparing the porous skeleton (2) by using the laser powder bed fusion technique is as follows:
• processing the titanium alloy powder (7) with the median diameter of 35 μm by adopting the laser powder bed fusion technique with a laser powder bed device (11) with process parameters of the scanning speed of 1200 mm/s and the laser power of 155 W, reducing, during a scanning process, a thermal stress between two adjacent layers by using a sawtooth pattern, and alternating a scanning angle by 90° on a previous layer.