Characterisation of magnesium oxide and its interface with α-Mg in Mg–Al-based alloys

Magnesium oxide (MgO) films and particles have been collected by pressurised filtration of a Mg-8.6wt%Al-0.67wt%Zn (AZ91D) alloy melt. The morphology of the oxides and their interfaces with the α-Mg phase were investigated by high-resolution transmission electron microscopy. It was found that the oxide films consisted of large numbers of sub-micrometre-sized MgO particles, and that melt shearing can effectively break up the oxide films and disperse the oxide particles. For the first time, orientation relationships (ORs) of OR I: [1?1?1]_MgO～2° from (0?0?0?1)_α-Mg and (0?1?1)_MgO?//[2?1?1?0)_α-Mg; and OR II: (1?1?1)_MgO//(1?1?0?1)_α-Mg and [0?1?1]_MgO//[1?2?1?1]_α-Mg, were observed between the MgO particles and the α-Mg matrix. The calculated Bramfitt planar disregistries were 5.5% and 2.5% for the two ORs, respectively, indicating good lattice matching between MgO and α-Mg at the interface. With the evidence of grain refinement effect observed in the sheared AZ91D magnesium alloy, the possibility of MgO particles to act as potent nucleants for heterogeneous nucleation of α-Mg grains is discussed in terms of the crystallographic criterion.     

TEM observation of oxide scale formed on a Ti–Al–Zr alloy oxidized at 360°C in alkaline steam

Ti–Al–Zr alloy has been oxidized at 360°C in alkaline steam at a pressure of 10.3?±?0.7?MPa. Cross-sectional transmission electron microscopy (TEM) observations indicated that the oxide scale of Ti–Al–Zr alloy was composed of outer and inner subscales, in which the outer layer consists of anatase-TiO₂ and the inner layer a mixture of TiO and Ti₂O. The thickness of the Ti₂O, TiO and anatase-TiO₂ were approximately 50, 100 and 400?nm, respectively. These results were confirmed by X-ray energy dispersive spectrometry (EDS) measurements. The enhanced corrosion of titanium alloys in LiOH solution is attributed to a high hexagonal Ti₂O to tetragonal TiO₂ phase transformation rate induced by the substitution of Li⁺ for Ti⁴⁺ in the oxide layer.     

Wear behaviour of a gradient surface produced by a punching process in a Cu-30 Ni alloy

The grain size variation in a gradient surface produced by a punching and recovery process on a Cu-30Ni alloy has been observed by atomic force microscopy. The friction characteristics of the gradient surface in a 3.5 wt% NaCl solution were investigated using a micro-indenter probe, a pin-on-disc type tribometer, a strain sensor and an optical microscope. The results showed that the hardness and grain size can be well represented by the Hall–Petch relationship when the gain size is more than 30?nm. The wear rate, friction coefficient and adhesive force all increase depth below the surface. These variations are attributed to a gradual increasing grain size with depth. The morphologies of the worn track were also studied to understand further the corrosive wear behaviour of gradient surfaces.     

Understanding scale-dependent yield stress of metals at micrometre scales

The mechanical softening behaviour of micrometre-scale metals (free-standing metal foils and wires) with decreasing either the geometrical or the microstructural scale (i.e. the smaller, the weaker) has recently been reported. Here, we present a mechanism-based model to understand the softening behaviour, which is based on competition between the effects of surface grain relaxation and the interior grain strengthening effect. The model describes well the yield stress of Cu foils with different ratios of the thickness to grain size.     

Proactive Personality and Employee Creativity: The Effects of Job Creativity Requirement and Supervisor Support for Creativity

This study examined the relationships between proactive personality and employee creativity and the moderating roles of job creativity requirement and supervisor support for creativity in activating proactive personality associated with employee creativity. To provide a rigorous test of the hypotheses, we conducted a field study from a sample of 157 employee–supervisor pairs in South Korea. The results revealed that a proactive personality was positively associated with employee creativity. In addition, job creativity requirement and supervisor support for creativity jointly influenced the relationship between proactive personality and employee creativity. Specifically, proactive employees exhibited the highest employee creativity when job creativity requirement and supervisor support for creativity were both high.     

Unconscious and out of control: Subliminal priming is insensitive to observer expectations

We asked whether the influence of an invisible prime on movement is dependent on conscious movement expectations. Participants reached to a central target, which triggered a directional prime–mask arrow sequence. Participants were instructed that the visible arrows (masks) would most often signal a movement modification in a specific (biased) direction. Kinematic analyses revealed that responses to the visible mask were influenced by participants’ intentional bias, as movements were fastest when the more probable mask was displayed. In addition, responses were influenced by the invisible prime without regard to its relationship to the more probable mask. Analysis of the time of initial trajectory modifications revealed that both primes influenced responses in a similar manner after accounting for participants’ bias. These results imply that invisible stimuli automatically activate their associated responses and that unconscious priming of the motor system is insensitive to the conscious expectations of the participant making the pointing movements.     

The Name-Pronunciation Effect: Further Evidence from Chinese

This study examined the Chinese name-pronunciation effect. The easy-to-pronounce and difficult-to-pronounce Chinese names were created using the same characters in order to control for visual perceptual and conceptual fluency. In Experiment 1, participants rated each name in terms of liking, electability as a state leader, income level, and baby name preference. An additional rating of prevalence was used to estimate familiarity. In Experiment 2, participants did not read the name aloud before rating and performed intentional recall and recognition tests. In both experiments, the easy-to-pronounce names were rated higher than difficult-to-pronounce names on liking. This effect generalized to judgments of electability and baby name preference but not to prevalence and income level. There were no differences in memory performances between the two types of names. Results are discussed in terms of the boundary condition of the name-pronunciation effect and the advantage of using Chinese names to study this effect.