Ultrasonic texture characterization of aluminum, zirconium and titanium alloys

This work attempts to show the feasibility of nondestructive characterization of non-ferrous alloys, specifically aluminum, zirconium, and titanium. Aluminum alloys have a small single crystal anisotropy which requires very precise ultrasonic velocity measurements for derivation of orientation distribution coefficients (ODCs); the precision in the ultrasonic velocity measurement required for aluminum alloys is much greater than is necessary for iron alloys or other alloys with a large single crystal anisotropy. To provide greater precision, some signal processing corrections need to be applied to account for the inherent, half-bandwidth offset in triggered pulses when using a zero-crossing technique for determining ultrasonic velocity. In addition, alloys with small single crystal anisotropy show a larger dependence on the single crystal elastic constants (SCECs) when predicting ODCs which require absolute velocity measurements. Attempts were made to independently determine these elastics constants in an effort to improve correlation between ultrasonically derived ODCs and diffraction derived ODCs.; The greater precision required to accurately derive ODCs in aluminum alloys using ultrasonic nondestructive techniques is easily attainable. Ultrasonically derived ODCs show good correlation with derivations made by Bragg diffraction techniques, both neutron and X-ray. The best correlations were shown when relative velocity measurements could be used in the derivations of the ODCs. Derivations of W{dollar}sb{lcub}400{rcub}{dollar}, which require absolute velocity measurements, were not terribly good, but this is because the SCECs strongly influence these derivations. Once the SCECs were independently determined for the particular alloy studied, the computations of W{dollar}sb{lcub}400{rcub}{dollar} improved.; Calculation of ODCs in materials with hexagonal crystallites can also be done. Because of the crystallite symmetries, more information can be extracted using ultrasonic techniques, but at a cost of requiring more physical measurements. Some industries which use materials with hexagonal crystallites, e.g. zirconium alloys and titanium, have traditionally used texture parameters which provide some specialized measure of the texture. These texture parameters, called Kearns factors, can be directly related to ODCs. Again, good correlations between ultrasonically determined ODCs and diffraction determined ODCs were found. In addition, Kearns parameters derived using ultrasonic techniques correlated well with Kearns parameters derived using neutron and X-ray diffraction.