机械合金化AlTiCrNiCu低密度高熵合金的粘结剂喷射3D打印与烧结致密化研究

Binder Jet 3D Printing and Sintering Densification of AlTiCrNiCu Low-Density High-Entropy Alloy Prepared by Mechanical Alloying

摘要:

粘结剂喷射3D打印（BJ3DP）技术因其独特优势而受到广泛关注，然而，粉末床打印工艺需要球形粉末，限制了一些熔点差较大的高熵合金粉末的制备以及打印成形。本工作主要针对非球形颗粒的BJ3DP-烧结行为开展研究。结果表明，采用机械合金化法制备了bcc结构的不规则AlTiCrNiCu低密度高熵合金粉末，其粒径分布为6.72~67.52 μm，平均粒径为21.17 μm，满足BJ3DP工艺要求。正交试验结果表明，在保证生坯形貌完整条件下：当粘结剂饱和度为70%、层厚为120 μm和铺粉速度为5 mm/s时，BJ3DP的生坯致密度较高（约44.4%）。生坯经过1190 ℃/4 h烧结后，其块体的致密度达到91.6%。AlTiCrNiCu低密度高熵合金为多相结构，基体为B2相，还包括bcc、fcc和少量L2₁相。该合金具有高的抗压缩性能，其屈服强度和抗压强度分别约为840和960 MPa。

Abstract:

The binder jet 3D printing (BJ3DP) process is currently a research hotspot. Generally, the powder bed printing process requires spherical powders, which limits the preparation and fabrication of some high-entropy alloy (HEA) powders with significant melting point differences. This study mainly focuses on the BJ3DP-sintering behavior of non-spherical particles. The results show that the non-spherical AlTiCrNiCu low-density HEA powder with bcc structure was prepared via mechanical alloying, with a particle size distribution of 6.72–67.52 μm and an average particle size of 21.17 μm, which complies with the process requirements of BJ3DP. The results of orthogonal experiment indicate that under the condition of ensuring green part morphology integrity, the higher green density (approximately 44.4%) is achieved in BJ3DP with a binder saturation of 70%, a layer thickness of 120 μm, and a powder spreading speed of 5 mm/s. After sintering at 1190 ℃ for 4 h, the relative density of the sintered sample reaches 91.6%. The AlTiCrNiCu low-density HEA exhibits a multiphase structure consisting of B2 phase as matrix, along with bcc, fcc, and a small amount of L2₁ phase. The AlTiCrNiCu low-density HEA exhibits high compressive properties, with a yield strength and compressive strength of approximately 840 and 960 MPa, respectively.