Abstract
Laser Engineered Net Shaping (LENS™) was used to produce a compositionally graded Ti-xMo (0 ≤ x ≤ 12 wt %) specimen and nine Ti-15Mo (fixed composition) specimens at different energy densities to understand the composition–processing–microstructure relationships operating using additive manufacturing. The gradient was used to evaluate the effect of composition on the prior-beta grain size. The specimens deposited using different energy densities were used to assess the processing parameters influence the microstructure evolutions. The gradient specimen did not show beta grain size reduction with the Mo content. The analysis from the perspective of the two grain refinement mechanisms based on a model known as the Easton & St. John, which was originally developed for aluminum and magnesium alloys shows the lower bound in prior-beta grain refinement with the Ti–Mo system. The low growth restriction factor for the Ti-Mo system of Q = 6,5C0 explains the unsuccessful refinement from the solute-based mechanism. The energy density and the grain size are proportional according to the results of the nine fixed composition specimens at different energy densities. More energy absorption from the material represents bigger molten pools, which in turn relates to lower cooling rates.
Highlights
In the recent years, several studies have been conducted to assess the influence of various alloys [1, 2] and additive manufacturing processing parameters [3, 4] on the microstructure evolution of titanium alloys
Knowing the microstructure is determinant to predict the properties of the material and for this reason, the effects of composition and processing parameters are critical for the development of new alloys
The expected columnar morphology of the prior-beta grains in additive manufactured specimens has been widely reported in several studies [12, 15, 33]
Summary
Several studies have been conducted to assess the influence of various alloys [1, 2] and additive manufacturing processing parameters [3, 4] on the microstructure evolution of titanium alloys. Knowing the microstructure is determinant to predict the properties of the material and for this reason, the effects of composition and processing parameters are critical for the development of new alloys. Additive manufacturing (AM) is associated with conditions that lie far away from the thermodynamic equilibrium, leading to lower solute partitioning compared to casting due to the rapid solidification nature of the process and the possibility to affect a range of compositions in a single specimen by adopting a combinatorial approach. There are several efforts to simulate the molten pool [7, 8] and the Mendoza et al BMC Chemistry (2019) 13:5 solidification process [9] in AM to understand and predict the microstructure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
