Effect of Minor Alloying Elements (C, Ni, Cr, Mo) on the Long-Term Corrosion Behaviors of Ultrahigh-Strength Automotive Steel Sheet in Neutral Aqueous Environment

This study examined the effects of minor alloying elements (C, Ni, Cr, and Mo) on the long-term corrosion behaviors of ultrahigh-strength automotive steel sheets with a tensile strength of more than 1800 MPa. A range of experimental and analytical results showed that the addition of Ni, Cr, and Mo decreased the corrosion current density and weight loss in electrochemical and immersion tests, respectively, in a neutral aqueous condition. This suggests that the minor addition of elements to steel can result in improved corrosion resistance even for long-term immersion periods. This is closely associated with the formation of thin and stable corrosion scale on the surface, which was enriched with the alloying elements (Ni, Cr, and Mo). On the other hand, their beneficial effects did not persist during the prolonged immersion periods in steel with a higher C content, suggesting that the beneficial effects of the minor addition of Ni, Cr, and Mo were overridden by the detrimental effects of a higher C content as the immersion time was increased. Based on these results, lower C and the optimal use of Ni, Cr, and Mo are suggested as a desirable alloy design strategy for developing ultrahigh-strength steel sheets that can be exposed frequently to a neutral aqueous environment.

A Dramatic Change in Rheological Behavior of a Clay Material Caused by a Minor Addition of Hydrophilic and Amphiphilic Polyelectrolytes

Wide usage of clay-based materials in industry requires investigations concerning efficient modification techniques to control their mechanical behavior in aqueous media. The challenging problem in this field involves minimization of the modifying agent content to provide marked changes in the operating characteristics of the material. In this work, the physicochemical, mechanical and structural aspects of the interaction of capillary water-saturated kaolinite with polyelectrolytes were studied. Modification of kaolinite with a negligible amount (0.1 wt.%) of hydrophilic and amphiphilic polyelectrolytes provides the control for rheological parameters of kaolinite suspensions such as storage and loss modulus in the range of three orders of magnitude. The results obtained reveal the wide possibilities for the production of a spectrum of clay materials using minor amounts of polymer modifying agents.

Change of Tensile Properties with Aging Time and Temperature in Al-Si-Cu-Mg 354 Cast Alloys with/without Minor Addition of Ni and/or Zr

The principal aim of the present research work was to investigate the effects of minor additions of nickel and zirconium on the strength of cast aluminum alloy 354 at room temperature (25°C). A decrease in tensile properties of ∼10% with the addition of 0.4 wt.% nickel is attributed to a nickel-copper reaction which interferes with the formation of Al2Cu precipitates. The platelet-like phases (Al,Si)3(Zr,Ni,Fe) and (Al,Si)3(Zr,Ti) are the main features observed in the microstructures of the tensile samples of alloys with Zr additions. The reduction in mechanical properties is due to the increase in the percentage of intermetallic phases formed during solidification; such particles would act as stress concentrators, decreasing the alloy ductility. The main effect of Zr addition lies in a significant reduction in the alloy grain size ∼40%, rather than an increase in the mechanical properties. Quality index charts could be used in assessing the effects of the Ni and Zr additions to the base alloy, as well as evaluating the heat treatment relationships to the alloy tensile properties, in particular when the system shows multiple precipitation reactions. Due to the high liquidus temperature of the Al-Zr binary phase diagram, addition of Zr beyond 0.2% is not recommended to avoid undissolved Zr.

The Anatomy of Consonance/Dissonance: Evaluating Acoustic and Cultural Predictors Across Multiple Datasets with Chords

Acoustic and musical components of consonance and dissonance perception have been recently identified. This study expands the range of predictors of consonance and dissonance by three analytical operations. In Experiment 1, we identify the underlying structure of a number of central predictors of consonance and dissonance extracted from an extensive dataset of chords using a hierarchical cluster analysis. Four feature categories are identified largely confirming the existing three categories (roughness, harmonicity, familiarity), including spectral envelope as an additional category separate from these. In Experiment 2, we evaluate the current model of consonance/dissonance by Harrison and Pearce by an analysis of three previously published datasets. We use linear mixed models to optimize the choice of predictors and offer a revised model. We also propose and assess a number of new predictors representing familiarity. In Experiment 3, the model by Harrison and Pearce and our revised model are evaluated with nine datasets that provide empirical mean ratings of consonance and dissonance. The results show good prediction rates for the Harrison and Pearce model (62%) and a still significantly better rate for the revised model (73%). In the revised model, the harmonicity predictor of Harrison and Pearce’s model is replaced by Stolzenburg’s model, and a familiarity predictor coded through a simplified classification of chords replaces the original corpus-based model. The inclusion of spectral envelope as a new category is a minor addition to account for the consonance/dissonance ratings. With respect to the anatomy of consonance/dissonance, we analyze the collinearity of the predictors, which is addressed by principal component analysis of all predictors in Experiment 3. This captures the harmonicity and roughness predictors into one component; overall, the three components account for 66% of the consonance/dissonance ratings, where the dominant variance explained comes from familiarity (46.2%), followed by roughness/harmonicity (19.3%).