Abstract
The solidification experiments of TC8 alloy under both microgravity and normal gravity were conducted using a drop tube. The solidification microstructure were found composed of fine equiaxed grains formed at early stage and bigger elongated grains formed at later stage. Between the two kinds of grains a curved transition interface was observed in 1g sample, while that in μg sample was almost flat. Generally, the amounts and aspect ratios of the grains are larger, and the grain sizes are smaller in 1g sample. Besides, no visible element macrosegregation occurred in both samples. The results suggest that the solidification velocities of the samples were rapid, and consequently the convection effect and solute transport effect caused by gravity had little influence on the solidification microstructure. Therefore, the solidification process was mainly controlled by thermal diffusion, and hydrostatic pressure and wall effect played a great role in it.
Highlights
With the continuous development of aerospace technology and advanced material preparation technology, people are looking for the perfect combination of the two technologies to serve the future deep space exploration and interstellar navigation
In order to better understand the effect of space microgravity environment on the solidification behavior of titanium alloy, so as to provide necessary technical support for its space additive manufacturing, it is necessary to conduct an experimental study on it in advance
According to the complete temperature–time curve of 1g sample, it can be seen that the top temperature of the sample dropped below the melting points after the power was turned off for about 2.5 s, that is, the solidification of the samples had finished before quenching in the silicon oil
Summary
With the continuous development of aerospace technology and advanced material preparation technology, people are looking for the perfect combination of the two technologies to serve the future deep space exploration and interstellar navigation. As a kind of typical light metal, titanium alloy has a series of excellent properties, such as high specific strength, good machining performance, strong corrosion resistance, etc., and is widely used in the aerospace field,[4,5,6] so it is expected to be a candidate material for additive manufacturing in space. In order to better understand the effect of space microgravity environment on the solidification behavior of titanium alloy, so as to provide necessary technical support for its space additive manufacturing, it is necessary to conduct an experimental study on it in advance. One of commonly used titanium alloys, TC8, was selected in this paper to conduct a comparative study on its solidification behavior in microgravity and gravity environments with a 50-m-high drop tube,[11,13,14,15] so as to obtain the specific influence of microgravity effect on the solidification of titanium alloys
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