利用选区激光熔化技术制备析出强化型高性能多主元合金存在难以成形的问题，极易开裂。本工作通过选区激光熔化制备Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ (含0.02%B，质量分数)多主元合金，揭示其裂纹形成机理，探索抑制裂纹形成的途径。结果表明，裂纹沿粗大柱状晶的晶界开裂，且优先出现在大角度晶界处，裂纹表面呈现光滑、清晰的树枝晶形貌，为典型的凝固裂纹。形成凝固裂纹的主要原因是：在凝固末期，B元素偏析于晶界，促进低熔点液膜产生，大角度晶界使得液膜保持稳定状态，循环加热/冷却导致的残余应力作用于液膜进而触发凝固开裂。热输入与开裂敏感性并非线性关系，仅通过调控热输入无法消除裂纹，只能在一定程度上抑制裂纹。通过添加TiB₂纳米颗粒，增加晶界密度，缓解局部应力集中，成功消除了凝固裂纹。

With the increasing sophistication of laser additive manufacturing technology, the need for high-performance alloys suitable for additive manufacturing has grown. Developing new alloys with excellent mechanical properties and good formability has become a critical direction in the field of additive manufacturing, but severe defect-like cracking remains a major concern. Based on a new design concept from the corners of the phase diagrams to the central region, multi-principal element alloys (MPEAs, i.e., high-entropy alloys) have introduced new opportunities for the development of high-performance additive manufactured alloys. Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ MPEA (containing 0.02%B element, mass fraction) shows great potential for overcoming the severe trade-off between manufacturability and high strength. On the one hand, Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ MPEA has a yield strength of ~1 GPa and an elongation of ~25%, thus its comprehensive performance is superior to that of most existing MPEAs. On the other hand, because of its slower precipitation kinetics than the IN718 alloy, the main strengthening phase ({\gamma }^{″}) of MPEA is stable at 800 ^oC, and thus it shows promise for eliminating the cracking of the precipitation-strengthened alloys. However, because Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ MPEA is a newly designed alloy, the effects of multi-principal alloying on its non-equilibrium solidification behavior are unknown, as is the mechanism of this effect, and its cracking behavior under additive manufacturing and corresponding mechanism must be evaluated. This work takes Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ MPEA as the research object and uses selective laser melting (SLM) technology and advanced characterization techniques to investigate the crack formation mechanism and control path of the alloy under different SLM process parameters. The formability of Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ alloy under different SLM process parameters was investigated, and the crack formation mechanism of Ni₅₈Cr₂₃Fe₁₀W₅Ti₂Ta₁Nb₁ alloy was revealed. The crack control method was then explored. The results showed that the cracks propagated along the grain boundary of the coarse columnar crystals and preferentially appeared at high-angle grain boundaries (HAGBs). The surface of the cracks presented a smooth and clear dendritic morphology, which is a typical solidification crack. At the terminal stage of solidification, the HAGB regions contain a thin layer of B segregation, which promoted the production of a continuous liquid film, and the liquid film remained stable at HAGB owing to the large grain boundary energy. The residual stress caused by heating/cooling circulation acted on the liquid film and triggered solidification cracking. The relationship between the heat input and the cracking sensitivity was not linear. Cracks cannot be eliminated by simply regulating heat input, and cracks can be suppressed only to a certain extent. The grain boundary density increased, local stress concentration was alleviated, and solidification cracks were successfully eliminated with the addition of TiB₂ nanoparticles.