Abstract
A metastable beta TMZF alloy was tested by isothermal compression under different conditions of deformation temperature (923 to 1173 K), strain rate (0.172, 1.72, and 17.2 s−1), and a constant strain of 0.8. Stress–strain curves, constitutive constants calculations, and microstructural analysis were performed to understand the alloy’s hot working behavior in regards to the softening and hardening mechanisms operating during deformation. The primary softening mechanism was dynamic recovery, promoting dynamic recrystallization delay during deformation at higher temperatures and low strain rates. Mechanical twinning was an essential deformation mechanism of this alloy, being observed on a nanometric scale. Spinodal decomposition evidence was found to occur during hot deformation. Different models of phenomenological constitutive equations were tested to verify the effectiveness of flow stress prediction. The stress exponent n, derived from the strain-compensated Arrhenius-type constitutive model, presented values that point to the occurrence of internal stress at the beginning of the deformation, related to complex interactions of dislocations and dispersed phases.
Highlights
TMZF is a metastable beta titanium alloy specially developed for medical applications
The microstructural analysis led to the conclusion that the primary softening mechanism of the TMZF alloy, within the range of temperatures and strain rates analyzed, was DRV
The TMZF’s high solute content, which led to a high value of SFE, promoted the prevalence of DRV mechanisms and delayed CDRX to higher values of temperature deformation
Summary
TMZF is a metastable beta titanium alloy specially developed for medical applications.Its main characteristics are the low elastic modulus associated with its cubic phase [1] and a chemical composition that avoids elements that have been identified as cytotoxic [2,3].The elastic modulus varies from 70 to 90 GPa, reducing stress shielding phenomena [1].Besides the low modulus, beta alloys have relatively good workability due to their low beta transus temperature compared to the conventional α + β titanium alloys [4].The flow stress behavior during the hot deformation process can be highly complex to predict since hardening and softening phenomena are influenced by numerous factors, such as the accumulated strain, strain rate, and temperature under which thermomechanical processing is performed. The elastic modulus varies from 70 to 90 GPa, reducing stress shielding phenomena [1]. Beta alloys have relatively good workability due to their low beta transus temperature compared to the conventional α + β titanium alloys [4]. The flow stress behavior during the hot deformation process can be highly complex to predict since hardening and softening phenomena are influenced by numerous factors, such as the accumulated strain, strain rate, and temperature under which thermomechanical processing is performed. The combination of processing parameters leading to metallurgical phenomena and the consequent microstructure modifications, along with the deformation evolution, directly impact the flow behavior. It is paramount to model or design thermomechanical processes to understand how the relationship between flow stress and strain interacts in metallic materials and alloys and the kinetics of metallurgical transformations to predict the final 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
