This study is devoted to studying the influence of plasma liquid-phase alloying on the physical and mechanical properties of the surface layer of tungsten and its alloys. Experimental samples of tungsten with copper and zirconium coatings were exposed to compression plasma flows (CPF). The elemental composition of the samples was determined by energydispersive X-ray spectroscopy (EDS), and lattice deformation and residual stresses were assessed using X-ray diffraction. The results of EDS showed that plasma exposure leads to the formation of a homogeneous alloy of tungsten and zirconium in a near-surface layer. Treatment of tungsten by CPF causes an increase in the level of lattice deformation. In the surface layer of W-CPF tensile stresses with a value up to 6 GPa were observed, while for the system alloyed with copper W-Cu, compressive stresses tending to zero were observed. For the W-Zr system, the maximum tensile stresses reached around 5–6 GPa. It has been established that the introduction of copper into tungsten significantly reduces the level of residual internal stresses compared to alloying with zirconium. The results obtained may contribute to the development of new tungsten alloys with improved performance characteristics for use in fusion energy and other fields.