Browse Topic: Alloys
Metastable β-titanium alloys have attracted considerable interest for structural applications, owing to their superior specific strength and the ability to obtain enhanced ductility through phase transformations induced by deformation. Nevertheless, in recently developed Ti-Zr-Al-V alloy systems, the interactions among dislocation slip, strain-induced martensitic transformation, and the consequent work-hardening response remains largely unclear. Under room-temperature uniaxial tension, this work systematically investigates how the microstructure evolves and how the alloy deforms for a metastable β-type Ti-42Zr-12Al-4V (at.%) alloy. To track the progression of strain-induced α″ martensite and dislocation activity across varying strain levels, techniques including quasi-in-situ scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and focused ion beam (FIB) were employed. Findings indicate that the dominant strengthening mechanism stems from the strain-induced α″ martensite blocking dislocation motion, alongside dislocation cross-slip. Although the martensite volume fraction rises with increasing strain, its growth rate diminishes at higher strains. The martensite and the β matrix exhibited a clear Burgers-type orientation relationship, namely [001]α″//[110]β. Moreover, the appearance of martensite inside both primary and secondary slip bands generates a dynamic Hall-Petch effect, which reduces the dislocation mean free path and thereby supports continued strain hardening. These results provide deeper insight into the transformation-induced plasticity (TRIP)-assisted deformation mechanisms active in β-type titanium alloys and could guide the development of strong yet ductile materials.
This specification covers a corrosion-resistant steel product in the solution and precipitation heat treated (H1075) condition, 4 inches (102 mm) and under in nominal thickness.
Impacts of laser shock peening (LSP) on the evolution characteristics of microstructure in commercially pure α-phase titanium (α-Ti) are explored by molecular dynamics (MD) simulations of high strain-rate compression. The EAM potential (Zhou potential) is selected for its ability to capture the evolution of microstructures. Considering the LSP-induced peak plasma pressure, the strain rate during the simulated shock compression process is set at 10^9 s-1 to replicate the LSP process. The stress-strain curve of the α-Ti under high strain-rate compression is obtained. The maximum equivalent stress reaches 3.6 GPa, consistent with the theoretically calculated value. The simulation results reveal that mechanical twins (MTs) are activated at a strain of 3%. The number of mechanical twins increases and eventually stabilizes, forming a network structure throughout the grains. In the meantime, numerous partial dislocations are generated adjacent to the grain boundaries. The dislocation density also increases with strain and dislocation reactions occur. Moreover, grain refinement is identified. The grain size is refined from the initial ~ 8 nm to ~ 4 nm in the polycrystalline α-Ti. Twinning, together with dislocation-mediated plasticity, drives the refinement of grain size. Gradients of twin density, dislocation density, and grain size density are induced by LSP on the surface of α-Ti. This study comprehensively investigates how LSP influences the evolution of microstructures by MD simulations. It develops an innovative numerical strategy that offers a foundation for elucidating the underlying mechanisms of LSP.
Researchers have received a $24.9 million grant to develop an NSF Materials Innovation Platform where universities, national laboratories and industry members can run alloy-discovery campaigns using robotic systems and artificial intelligence. Texas A&M University, College Station, Texas A six-year, $24.9 million grant from the U.S. National Science Foundation (NSF) will establish the Autonomous Robotic Metallurgist Materials Innovation Platform (ARM-MIP) at Texas A&M University - a national user facility where robots and artificial intelligence take on the repetitive labor of alloy discovery, freeing scientists to focus on discovery itself. ARM-MIP will be sited at The Texas A&M University System RELLIS Campus in Bryan, a dedicated research campus that also hosts the Texas A&M Engineering Experiment Station and the U.S. Army Transformation and Training Command's central testing hub at the George H.W. Bush Combat Development Complex. The platform is designed to reach more than 200 users a year and 50 alloys per month in its first year, scaling to more than 200 alloys per month by year six.
Materials engineers have developed the ability to manipulate structure and matter at the nanoscale for solid-state alloys called intermetallics, making it possible to alter their properties for extra performance characteristics. Purdue University, West Lafayette, IN Intermetallics, which consist of two or more metallic elements in an ordered, crystal structure, are especially good candidates for these enhanced physical and chemical properties, owing to the critical role they play in demanding applications and products such as jet engines, gas turbines, and energy storage and automotive systems. The remarkable strength, high melting temperatures and superior creep resistance of intermetallics make them indispensable for structural usage in extreme environments. In a paper published in Science Advances, Purdue University engineers demonstrated a way to achieve simultaneous high strength and plasticity in cobalt aluminum (CoAl) intermetallics.
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