Development
of high-entropy alloy (HEA) films is a promising and cost-effective
way to incorporate these materials of superior properties in harsh
environments. In this work, a refractory high-entropy alloy (RHEA)
film of equimolar CuMoTaWV was deposited on silicon and 304 stainless-steel
substrates using DC-magnetron sputtering. A sputtering target was
developed by partial sintering of an equimolar powder mixture of Cu,
Mo, Ta, W, and V using spark plasma sintering. The target was used
to sputter a nanocrystalline RHEA film with a thickness of ∼900
nm and an average grain size of 18 nm. X-ray diffraction of the film
revealed a body-centered cubic solid solution with preferred orientation
in the (110) directional plane. The nanocrystalline nature of the
RHEA film resulted in a hardness of 19 ± 2.3 GPa and an elastic
modulus of 259 ± 19.2 GPa. A high compressive strength of 10
± 0.8 GPa was obtained in nanopillar compression due to solid
solution hardening and grain boundary strengthening. The adhesion
between the RHEA film and 304 stainless-steel substrates was increased
on annealing. For the wear test against the E52100 alloy steel (Grade
25, 700–880 HV) at 1 N load, the RHEA film showed an average
coefficient of friction (COF) and wear rate of 0.25 (RT) and 1.5 (300
°C), and 6.4 × 10–6 mm3/N m
(RT) and 2.5 × 10–5 mm3/N m (300
°C), respectively. The COF was found to be 2 times lower at RT
and wear rate 102 times lower at RT and 300 °C than
those of 304 stainless steel. This study may lead to the processing
of high-entropy alloy films for large-scale industrial applications.
Duplex stainless steel, 71 wt.% austenite, 13 wt.% ferrite and 16 wt.% sigma, was made upon heat treating of fully ferritic as-built selective laser melted (SLM) 2507 stainless steel at 1200 °C. Formation of sigma phase in the heat treated SLM 2507 was investigated using optical microscopy and scanning electron microscopy (SEM). The heat treated SLM 2507 demonstrated a yield strength of 686 MPa, ultimate tensile strength of 920 MPa and an elongation of 1.8% at room temperature with a brittle fracture morphology. Precipitation of sigma phase during heat treatment and slow cooling improved the mechanical and wear properties at high temperatures (1200 °C and 800 °C, respectively). The tensile strength and elongation of the heat treated SLM 2507 was measured 400 MPa and 20% as compared to casted duplex steel with 19 MPa and 30% elongation at 1200 °C. The 20 times higher mechanical strength as compared to casted duplex steel was attributed to sigma precipitates. Tribological behaviour of heat treated duplex SLM 2507 containing sigma at 800 °C showed very low wear rate of 4.5 × 10−5 mm3/mN compared to casted duplex steel with 1.6 × 10−4 mm3/mN.
As scientists within the field of battery research we may often find it quite difficult to match and trust the promises given in press releases and high-profile papers. Even though there are real breakthroughs, where the results indeed are as impressive as they are marketed to be, we may as often find the reporting of "revolutionary" results to omit critical aspects of the methods and materials used. The absolute majority of researchers do not actively pursue to present their science in any untrue fashion, but poor (ethical) judgement could affect anyone working long hours in a gloomy lab at dusk and at the same time feel being pressed for publications and citations. Here, we outline ten ways to make your results appear more attractive and groundbreaking than they actually are, especially to laypeople that might not appreciate the full range of difficulties associated with battery research. Consider it a light-hearted entry with respect to scientific quality in methodology and dissemination, that might assist you in looking for nebulous reporting practices in your own and your peers' work, but please do not consider it a guide, but a humorous contrast to the real publishing guidelines recently launched. [2][3][4] 1. Always compare your results against the state-of-the-art from 2010
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