## 1 Introduction  
Because of its high melting point of 3422 \({}^{\circ}\)C, W has become the preferred material in applications such as heating, electrical, and welding [1]. Pure W requires a sintering temperature as high as 2700 \({}^{\circ}\)C to be sintered to full density. Such high temperatures impose limitations on the fabrication/preparation of W materials that are sintered to full density. Low-temperature sintering techniques for W have been investigated extensively. German [2] investigated low-temperature sintering of W in the temperature range of 1050-1400 \({}^{\circ}\)C. The study demonstrated that the addition of Group VIII transition metals such as Ni, Pd, Pt, Co, and Fe can enhance the sintering kinetics of W powder, reducing its sintering temperature. Notably, Pd was found to be the most effective activated sintering additive. [PERSON] [1] utilised Ni and Fe as additives for activated sintering of W in the temperature range of 1177-1250 \({}^{\circ}\)C. As the Ni content increased, the activation energy decreased, and the diffusion coefficient increased, indicating that Ni-doped W exhibited superior sintering kinetics compared with Fe and (Fe+Ni) doping. [PERSON] [3] studied the microstructure of pure W and Ni-doped W at a sintering temperature of 1200 \({}^{\circ}\)C. The microstructure of pure W exhibited a polycrystalline grain boundary and multiphase surface structure, whereas the Ni-doped grains exhibited reduced polycrystalline grain boundaries and a more rounded surface. This indicates that the Ni-induced grain boundary structural transition can lead to the activated sintering of W.  
The combination of W and Ag offers the advantages of W's high melting point, arc corrosion resistance, high oxidation resistance, and high hardness, along with Ag's high electrical and thermal conductivity, as well as its excellent ductility. AgW materials exhibit excellent comprehensive performance and can serve as substitutes for pure Ag or Ag alloy contact materials in switch applications, reducing the consumption of Ag. Consequently, AgW has become an indispensable key material in low-voltage electrical switches [4; 5; 6; 7]. AgW materials''self-spontaneous sweating cooling' mechanism allows their utilisation at temperatures exceeding 3000 \({}^{\circ}\)C, making them useful in fields such as aerospace, electronic engineering, and metallurgy. The preparation methods include the mixed-pressing sintering method [8], the infiltration method [9; 10; 11; 12; 13; 14], the activated liquid-phase sintering method [15; 16], mechanical alloying [17; 18; 19], the chemical co-precipitation-hydrogen reduction method [20; 21], and the sol-gel method [22; 23]. The infiltration method is one of the primary techniques used for producing AgW composite materials. Owing to the immiscibility of W and Ag, their sintering performance is relatively poor, making it challenging to sinter them to full density and form a homogeneous microstructure. Compared with conventional powder metallurgy methods, the infiltration method has advantages such as a high density, good sintering performance, and excellent electrical and thermal conductivity. However, in most studies, the infiltration temperature ranged from 1150 to 1350 \({}^{\circ}\)C, and the W content of the prepared AgW materials was in the range of 50-75%. There is a scarcity of literature on low-temperature sintering-infiltration below 1100 \({}^{\circ}\)C.  
In this study, the sintering of W with the addition of Cu and Ni was investigated at temperatures ranging from 950 to 1050 \({}^{\circ}\)C. The optimal sintering parameters were determined through shrinkage rate, density, and morphology analyses to obtain excellent W skeletons. Subsequently, AgW (70 wt%), AgW (75 wt%), AgW (80 wt%), and AgW (85 wt%) materials were prepared through infiltration at 1050 \({}^{\circ}\)C, and a comprehensive analysis was conducted to investigate the physical properties, morphologies, energy spectra, and metallographic microstructures of the high-W contact materials.