High-entropy alloys (HEAs) and compositionally complex alloys (CCAs) represent new classes of materials containing five or more alloying elements (concentration of each element ranging from 5 to 35 at. %). In the present study, HEAs are defined as single-phase solid solutions; CCAs contain at least two phases. The alloy concept of HEAs/CCAs is fundamentally different from most conventional alloys and promises interesting properties for industrial applications (e.g., to overcome the strength-ductility trade-off). To date, little attention has been paid to the weldability of HEAs/CCAs encompassing effects on the welding metallurgy. It remains open whether welding of HEAs/CCAs may lead to the formation of brittle intermetallics and promote elemental segregation at crystalline defects. The effect on the weld joint properties (strength, corrosion resistance) must be investigated. The weld metal and heat-affected zone in conventional alloys are characterized by non-equilibrium microstructural evolutions that most probably occur in HEAs/CCAs. The corresponding weldability has not yet been studied in detail in the literature, and the existing information is not documented in a comprehensive way. Therefore, this study summarizes the most important results on the welding of HEAs/CCAs and their weld joint properties, classified by HEA/CCA type (focused on CoCrFeMnNi and Al_xCoCrCu_yFeNi system) and welding process.

高熵合金（HEA）和成分复杂的合金（CCA）代表了包含5种或5种以上合金元素（每种元素的浓度范围为5至35 at。％）的新型材料。在本研究中，HEA被定义为单相固溶体。CCA至少包含两个阶段。HEA / CCA的合金概念与大多数常规合金根本不同，并承诺在工业应用中具有有趣的性能（例如，克服强度-延展性的权衡问题）。迄今为止，很少关注HEA / CCA的可焊性，包括对焊接冶金的影响。HEA / CCA的焊接是否会导致脆性金属间化合物的形成并促进晶体缺陷处的元素偏析尚无定论。对焊接接头性能的影响（强度，耐腐蚀性）必须进行调查。常规合金中的焊接金属和热影响区的特征是非平衡的微观结构演变，这种变化很可能发生在HEA / CCA中。相应的可焊性尚未在文献中进行详细研究，并且现有信息尚未得到全面记录。因此，本研究总结了按HEA / CCA类型分类的HEA / CCA焊接及其焊接接头性能的最重要结果（重点是CoCrFeMnNi和Al 现有信息未得到全面记录。因此，本研究总结了按HEA / CCA类型分类的HEA / CCA焊接及其焊接接头性能的最重要结果（重点是CoCrFeMnNi和Al 现有信息未得到全面记录。因此，本研究总结了按HEA / CCA类型分类的HEA / CCA焊接及其焊接接头性能的最重要结果（重点是CoCrFeMnNi和Al_x CoCrCu _y FeNi系统）和焊接工艺。