Application of the Hall-Petch Relation to Microhardness Measurements on Al, Cu, Al-MD 105, and Al-Cu Alloys

Taha, Ahmed; Hammad, F.H.

doi:10.1002/pssa.2211190207

Cited by 80 publications

(32 citation statements)

References 12 publications

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“…The alloys in this study also exhibit a linear relationship of hardness to grain size that follows the Hall-Petch relationship (see Figure 10) and was reported before for aluminum alloys (Taha and Hammad, 1990). It can be described with reasonable security by Equation 3 with K HV and H 0 being constants that were determined experimentally (see Table 3).…”

Section: Grain Sizessupporting

confidence: 86%

Wide Range Mechanical Customization of Mg-Gd Alloys With Low Degradation Rates by Extrusion

et al. 2019

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Currently, only a few magnesium alloys have been approved for implant applications. For biomedical purposes, the choice of the alloying elements is a critical parameter and rare earth elements have been proven to be mechanically suitable and biologically tolerable. In this comprehensive study, tailoring the mechanical properties of binary Mg-Gd alloys by indirect extrusion is shown to obtain a property profile that is applicable to different biomedical applications. Mg-2Gd, Mg-5Gd, and Mg-10Gd were solid solution treated before extrusion. For each alloy various combinations of extrusion temperature and speed were applied. Resulting effects of alloy composition and processing on microstructure development, texture evolution, mechanical properties, and degradation behavior were investigated. Grain sizes and corresponding textures were adjusted by the extrusion parameters. Despite changes in the texture, grain boundary strengthening effects were confirmed for all alloys in accordance with the Hall-Petch relationship. The alloy composition contributed to the mechanical properties by solid solution strengthening and a combination of texture changes and slip activities. Consequently, mechanical properties can be tailored within a wide range resulting in tensile yield strengths of 90 to 200 MPa (ultimate tensile strengths 180-280 MPa) and compressive yield strengths of 80 to 220 MPa (ultimate compressive strengths 300-450 MPa) with elongations of 10-45%. Low degradation rates in the range of 0.2 mm/year were determined for all alloys. Degradation was only slightly influenced by the alloy composition but not affected by processing. Overall, the properties of Mg-Gd determined in this work appear to be suitable to future implant applications.

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Section: Grain Sizessupporting

confidence: 86%

Wide Range Mechanical Customization of Mg-Gd Alloys With Low Degradation Rates by Extrusion

et al. 2019

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“…These hard particles strengthened the surface and offered greater resistance to the indentation produced by the indenter and a similar pattern was observed by another researcher [14]. Several factors influenced the strengthening of the composite, according to Hall-Petch theory, enhancement of hardness could be attributed to grain boundary strengthening [15]. The higher concentration of second phase titanium carbide reinforcement particles on the outer periphery (1 mm) resulted in decreased grain size of the matrix.…”

Section: Hardness Testingsupporting

confidence: 72%

Characterization of mechanical properties and three‐body abrasive wear of functionally graded aluminum LM25/titanium carbide metal matrix composite

Radhika

Raghu

2017

Materialwissenschaft Werkst

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Several engineering components require location specific performance under operating conditions. A compositional/microstructural gradient can provide the performance required at specific locations and these materials were named as functionally graded materials. Functionally graded aluminium metal matrix composites were generally established for the tribo‐components where high wear resistance was a necessity. Reports on three body abrasive wear behaviour of functionally graded materials was limited to date. In the present work, a new functionally graded system comprising aluminium/titanium carbide (10 wt%) was produced through stir casting route followed by centrifugal casting technique and its three body abrasive wear behaviour was investigated. Hollow cylindrical part with the dimensions of length 150 mm, outer diameter 150 mm and thickness 16 mm was obtained. Microstructural study was performed on outer (1 mm) and inner surface (13 mm) to analyze the compositional gradient across the thickness of the functionally graded composite. Hardness was measured on different surfaces along the radial distance from outer periphery and tensile test was conducted on the outer and inner zone. Abrasive wear test was conducted on different surfaces of the functionally graded composite under various loads and speeds at constant time. The microstructural results revealed that particle segregation was more at the outer surface and less at the inner surface. Wear test results showed that increase in wear rate was obtained with increase of load and decrease in wear rate was obtained with increase of speed. The outer surfaces of the functionally graded composite had greater mechanical properties and better wear resistance compared to other surfaces. Scanning electron microscopy analysis was done on the abraded surfaces and observed wear mechanisms were interpreted.

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“…The phase transformations discussed so far were accompanied by refined crystallite size in the heat treated coatings. This could have contributed to the improved microhardness of the heat treated coatings as explained by the Hall-Petch effect, which describes how the microhardness of non-work hardened bulk material can increase with a reduction in grain size [57,58]. The microhardness values of the coatings were nonetheless below those reported by Murray et al [6] for Al2O3 coatings sprayed with the same UTP TopGun.…”

Section: 3)mentioning

confidence: 79%

Suspension high velocity oxy-fuel (SHVOF) spray of delta-theta alumina suspension: Phase transformation and tribology

Owoseni

Murray

Pala³

et al. 2019

Surface and Coatings Technology

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Suspension high-velocity oxy-fuel (SHVOF) thermal spray is an emerging spray technology that enables the processing of nanometric feedstock. Although SHVOF thermal sprayed alumina coatings prepared from alpha alumina feedstock have been widely reported, a metastable δ-θ Al2O3 feedstock has yet to be investigated despite its low cost and commercial availability. In this study, an aqueous δ-θ Al2O3 suspension was sprayed on to a stainless steel (SS 304) substrate via SHVOF thermal spraying using an internal injection UTP TopGun. Xray diffraction (XRD) of the as-sprayed coating showed δ-θ Al2O3 to γ-Al2O3 transformation upon spraying, along with amorphous/nanocrystalline phase formation. Furthermore, postspray heat treatment of the coatings was performed at 600-750 °C for 6 and 48 h. The microhardness and indentation fracture toughness of the heat treated coatings increased by a factor of two compared to the as-sprayed coatings: due to grain refinement, pore consolidation and phase transformation of amorphous and γ-Al2O3 to δ-Al2O3. Unlubricated sliding wear tests were conducted at room temperature (~ 25 °C, relative humidity ~ 60 %) using α-Al2O3 balls (Ø 9.5 mm) as the counter body at a normal load of 16.8 N to study the wear performance of the coatings. The wear rate of the as-sprayed coating and the coating heat treated at 600 °C for 6 h is of the order of 10-9 mm 3 (Nm)-1 , a noticeable improvement over conventional alumina coatings. The coatings heat treated at 750 °C for both 6 and 48 h failed abruptly by severe wear due to their pre-cracked surface.

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Application of the Hall-Petch Relation to Microhardness Measurements on Al, Cu, Al-MD 105, and Al-Cu Alloys

Cited by 80 publications

References 12 publications

Wide Range Mechanical Customization of Mg-Gd Alloys With Low Degradation Rates by Extrusion

Wide Range Mechanical Customization of Mg-Gd Alloys With Low Degradation Rates by Extrusion

Characterization of mechanical properties and three‐body abrasive wear of functionally graded aluminum LM25/titanium carbide metal matrix composite

Suspension high velocity oxy-fuel (SHVOF) spray of delta-theta alumina suspension: Phase transformation and tribology

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