The strain-rate sensitivity exponent m and activation volume υ∗ are often used to characterize the strain-rate sensitivity of strength behavior in metals and alloys. Complications can arise when the m and υ∗ values become indeterminate, due to factors such as an inherent scatter in the mechanical property data. The study of commercial Ti-alloy wires is considered wherein to overcome this limitation, the formulation of the Kocks–Mecking (K–M) model is modified to provide a parameter cb that characterizes the microstructural scale responsible for the observed plasticity and work hardening behavior. The softening factor cb is found to be independent of strain-rate for the Ti-alloy wires of this study. It is proposed that cb !can offer a versatile and complementary computation to the activation volume υ∗ since its formulation includes the yield and ultimate strength values along with the plastic strain. For the tensile testing of Ti-alloy wires, a low cb-value of 14 is calculated for Ti-6Al-4V that is consistent with >10 % plasticity during work hardening whereas a high cb-value of 135 for Ti-6Al-7Nb corresponds with <4 % plasticity.

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Young's modulus of nanocrystalline metal coatings is measured using the oscillating, that is, tapping, mode of a cantilever with a diamond tip. The resonant frequency of the cantilever changes when the diamond tip comes in contact with a sample surface. A Hertz-contact-based model is further developed using higher-order terms in a Taylor series expansion to determine a relationship between the reduced elastic modulus and the shift in the resonant frequency of the cantilever during elastic contact between the diamond tip and sample surface. The tapping mode technique can be used to accurately determine Young's modulus that corresponds with the crystalline orientation of the sample surface as demonstrated for nanocrystalline nickel, vanadium, and tantalum coatings.

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Copper-Nickel-Carbon nanocomposite coatings are synthesized by the sequential sputter deposition of carbon (C) and a copper-nickel (Cu 1-x Ni x ) alloy. A distinct transition occurs as the Ni content (x) is increased from 0 to 1.00 during the Cu 1-x Ni x alloy deposition. The coating morphology changes from a dispersion of metallic Cu-particles in a C matrix to a well-defined nanolaminate structure. Between these morphological forms, a new prototype nanocomposite is produced at a Ni concentration (x) of 0.1-0.4 with the appearance of an interpenetrating matrix structure of C and Cu(Ni). This morphological structure has both a high 24-27 GPa hardness (H) and a low elastic modulus (E) of 144-169 GPa that results in a record high values of H/E at 1/6 and a H 3 /E 2 at 0.67-0.69 GPa in a novel compliant and hard coating.