The coupling efficacy of sintering temperature and pressure assistant densification of core-shell structured pure Ti

The densification behavior of core-shell structures under low-temperature high-pressure (LTHP) spark plasma sintering (SPS) is rarely revealed. Therefore, this study successfully achieved dense core-shell structured Ti through LTHP SPS, and investigated the coupling influence of temperature-pressure on densification behavior using molecular dynamics simulations. Experimental results indicate that 600 °C/400 MPa represents the optimal LTHP SPS condition for preparing dense core-shell structured Ti bulk without excessive grain growth. This inhibition of grain growth is attributed to the distinct densification behavior of LTHP SPS compared with conventional SPS method. Specifically, under conventional SPS, densification primarily occurs during the heating and holding stages, with plastic flow involved in initial heating stage transitioning to atomic diffusion driven by high temperatures dominating the subsequent sintering process. In contrast, LTHP SPS exerts a more pronounced effect on densification during the heating stage, where plastic flow is the dominant mechanism, accompanied by limited atomic diffusion due to lower temperatures. Entering the holding stage, plastic flow, atomic diffusion, and atomic migration all contribute to mild densification. Cooling predominantly involves atomic oscillations. This study not only provides critical insight into the densification mechanisms of LTHP SPS but also offers significant guidance on obtaining dense heterostructural metals by LTHP SPS technology.