In this study, the effect of Fe addition on the phase stability and corrosion resistance of Ti-15%Cr alloys was investigated. The alloying phenomenon in the specimens was also investigated to determine the effectiveness of the application of pure metallic powders as raw materials for the powder metallurgy method. Ti-15%Cr-1%Fe alloys exhibited needle-like structures within equiaxed structures, while Ti-15%Cr-5%Fe and Ti-15%Cr-10%Fe alloys only showed equiaxed grains. XRD results showed that the β phase could be stabilized by the addition of 5% or more Fe to the alloy. Although the pure powders were used as raw materials, the designated chemical composition, i.e. Ti-15%Cr-(1~10)%Fe can be achieved during sintering. The alloying phenomenon occurred upon sintering due to the high diffusivity of Cr and Fe within the β Ti matrix. The corrosion resistance of the newly developed Ti-15%Cr alloys was significantly improved compared with a commercial Ti-6%Al-4%V alloy.
This study aimed to investigate the effects of element diffusion on the alloying behaviour and microstructure of a Ti-10%Mo10%Cr
alloy during sintering and furnace cooling. A theoretical calculation of the average diffusion distance for each
element was performed to predict the alloying behaviour during sintering and furnace cooling. The Ti-10%Mo-10%Cr
alloy was fabricated using a blended element powder metallurgy approach. Micrograph of the samples after sintering
showed bright-circle structures and significantly decreased equiaxed structures. The number of plate-like structures
increased with prolonged sintering time. Microstructural changes occurred because of element diffusion resulting from
the prolonged sintering time. Moreover, the diffusion distance of each element also increased with prolonged sintering
time. Although elements can sufficiently diffuse during both sintering and furnace cooling, the diffusion distance during
sintering was considerably higher than that during furnace cooling for all elements. The diffusion distances of Cr and
Mo were the highest and lowest, respectively, during sintering and furnace cooling. This study showed that alloying
behaviour mostly occurred during sintering and was controlled by the diffusion of Mo atoms.