AMP_04_May_June_2021_Digital_Edition

1 0 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 1 Vulcan helped the researchers better understand the nature of such inter- nal stresses and their evolution under simultaneous high temperature and high-pressure conditions. The neu- tron data allowed characterization of phase-specific elastic strain, calculated from various diffraction peak param- eters with respect to the applied load direction. Researchers used these strains, in conjunction with the pro- posed mathematical model, to esti- mate the internal resistance to internal or back-stress in the deformed alloys. The resulting novel methodologies that combine state-of-the-art in situ neutron measurements and validated mathe- matical models will be broadly useful for the characterization of mechanical properties of components under rel- evant conditions and for the design of newmaterials that offer greater reliabil- ity and longevity of industrial compo- nents. The research was funded by the Advanced Technology Program of GE Research, GE Aviation, and GE Power. ornl.gov. TESTING | CHARACTERIZATION IMPROVING MICROMETERS Manufacturers are working with fibers and wires much thinner than they had even a decade ago for optical communications and on-chip electrical networks. This has driven the need for a laser micrometer that can measure tiny diameters with high accuracy and establish standard diameter master fibers that can be used as references to assess the diameter of other fibers. At the other end of the scale, there is a growing need to measure the size of large, centimeter-diameter pressure pistons and cylinder gauges. Now, researchers at the National Institute of Standards and Technology (NIST), Gaithersburg, Md., have developed a dramatically improved laser-based instrument that can more accurately m easure both ends of the spectrum. Called a laser micrometer, the device’s accuracy equals that of its state-of-the-art counter- parts but is cheaper, sim- pler to operate, and easier to maintain. The new micrometer uses an advanced laser dis- placement interferometer that relies on light to mea- sure the thickness of objects held between two metal contacts. Researchers now can measure the diameter of any object less than 50 millimeters wide, including fine-gauge wires and fibers. The new micrometer was fabricated almost entirely out of Invar, a nickel-iron alloy known for its thermal stability, making the device less prone to error than other advanced instru- men ts. nist.gov. UNDERSTANDING DEFORMATIONS In a new study at the DOE’s Oak Ridge National Laboratory (ORNL), Tenn., researchers conducted in situ neutron scattering measurements using the Vulcan instrument at the lab’s Spallation Neutron Source user facility. In nickel-based superalloys comprising a metal matrix with embedded parti- cles for reinforcement, the evolution of internal stresses created by extreme operating conditions leads to creep and metal memory of prior deformations. The Vulcan system has two mechanical arms that apply pressure and heating coils to induce high temperatures. Inset, a gas turbine. Courtesy of ORNL/Jill Hemman. Triangular holes make this material more likely to crack from left to right. Courtesy of N.R. Brodnik et al./ Phys. Rev. Lett. Atlas Evaluation & Inspection Services, South Plainfield, N.J., announced its first-ever Goel Ultrasonic Testing (UT) Challenge, to be held December 3-4 at the company’s headquarters. Participants must be UT Level II (SNT-TC-1A/ISO 9712) with at least two years of structural UT experience. The winner will take home a $5000 Grand Prize. To learn more and sign up, visit the website. www.aeis.com/GOELUT. BRIEF In the NIST micrometer, a laser beam is halved by the beam splitter cube (1). One part remains in the cube serving as the reference beam. The other part hits the retroreflector (2). As the floating carriage (3) moves away from the splitter cube and toward the back end of the anvil (4), the distance between the retroreflector and cube splitter varies (5). When the two beams rejoin, the laser reports the change in distance. Courtesy of NIST.