Search Results - "StJohn, D. H."

Grain structure control during metal 3D printing by high-intensity ultrasound by Todaro, C. J., Easton, M. A., Qiu, D., Zhang, D., Bermingham, M. J., Lui, E. W., Brandt, M., StJohn, D. H., Qian, M.

“…Additive manufacturing (AM) of metals, also known as metal 3D printing, typically leads to the formation of columnar grain structures along the build direction…”
Get full text

The Contribution of Constitutional Supercooling to Nucleation and Grain Formation by StJohn, D. H., Prasad, A., Easton, M. A., Qian, M.

“…The concept of constitutional supercooling (CS) including the term itself was first described and discussed qualitatively by Rutter and Chalmers in order to…”
Get full text

Trace Carbon Addition to Refine Microstructure and Enhance Properties of Additive-Manufactured Ti-6Al-4V by Mereddy, S., Bermingham, M. J., Kent, D., Dehghan-Manshadi, A., StJohn, D. H., Dargusch, M. S.

“…Carbon is a powerful alloying element for titanium alloys. In this work, trace carbon is alloyed with Ti-6Al-4V during wire + arc additive manufacturing, and…”
Get full text

Microstructure and Mechanical Properties of Long Ti-6Al-4V Rods Additively Manufactured by Selective Electron Beam Melting Out of a Deep Powder Bed and the Effect of Subsequent Hot Isostatic Pressing by Lu, S. L., Tang, H. P., Ning, Y. P., Liu, N., StJohn, D. H., Qian, M.

“…An array of eight long Ti-6Al-4V rods (diameter: 12 mm; height: 300 mm) have been additively manufactured, vertically and perpendicular to the powder bed, by…”
Get full text

Improved prediction of the grain size of aluminum alloys that includes the effect of cooling rate by Easton, M.A., StJohn, D.H.

“…A comprehensive study of the effect of cooling rate on the grain size of a range of grain refined wrought aluminum alloys was carried out under quiescent…”
Get full text

Grain refinement efficiency and mechanism of aluminium carbide in Mg–Al alloys by Lu, L., Dahle, A.K., StJohn, D.H.

“…Detailed microscopic examination using optical and electron microscopes suggests that Al 4C 3, often observed in the central regions of magnesium grains on…”
Get full text

The effect of solute on ultrasonic grain refinement of magnesium alloys by Qian, M., Ramirez, A., Das, A., StJohn, D.H.

“…An experimental study has been conducted to assess the structural refinement of magnesium and its alloys by ultrasonic irradiation during solidification. It is…”
Get full text

Surface alloying of AZ91E alloy by Al–Zn packed powder diffusion coating by Hirmke, J., Zhang, M.-X., StJohn, D.H.

“…A new surface coating technique, namely packed powder diffusion coating (PPDC), for AZ91E magnesium alloy is reported. This new technique uses a powder mixture…”
Get full text

Heterogeneous nucleation of Mg–Al alloys by Lu, L., Dahle, A.K., StJohn, D.H.

“…Grain size is one of the most important microstructural characteristics determining the mechanical properties and therefore the service performance of…”
Get full text

The role of solute in grain refinement of magnesium by LEE, Y. C, DAHLE, A. K, STJOHN, D. H

“…The effect of separate solute additions of Al, Zr, Sr, Si, and Ca on grain size of Mg has been investigated. Increasing the Al content in hypoeutectic Mg-Al…”
Get full text

A model of grain refinement incorporating alloy constitution and potency of heterogeneous nucleant particles by Easton, M.A, StJohn, D.H

“…A model for the determination of relative grain size is developed based on the assumption that nucleant substrates are activated by constitutional undercooling…”
Get full text

Recent advances in grain refinement of light metals and alloys by Easton, M.A., Qian, M., Prasad, A., StJohn, D.H.

“…•The interdependence of nucleation and growth determines grain size.•Epitaxial growth and the formation of metastable clusters in the melt may facilitate…”
Get full text

The Loss of Dissolved Zirconium in Zirconium-Refined Magnesium Alloys after Remelting by Qian, Ma, Hildebrand, Z.C.G., StJohn, D.H.

“…Magnesium–rare earth–zirconium (Mg-RE-Zr) materials are a high value-added class of speciality alloys used chiefly for aerospace applications, where the use of…”
Get full text

Controlling the microstructure and properties of wire arc additive manufactured Ti–6Al–4V with trace boron additions by Bermingham, M.J., Kent, D., Zhan, H., StJohn, D.H., Dargusch, M.S.

“…This study demonstrates that trace boron addition to Ti–6Al–4V coupons produced by additive layer manufacturing is an effective way to eliminate the…”
Get full text

Effect of iron on grain refinement of high-purity Mg–Al alloys by Cao, P., Qian, Ma, StJohn, D.H.

“…The effect of iron on the grain refinement of high-purity Mg–3%Al and Mg–9%Al alloys has been investigated using anhydrous FeCl 3 as an iron additive at 750 °C…”
Get full text

A New Analytical Approach to Reveal the Mechanisms of Grain Refinement by StJohn, D. H., Cao, P., Qian, M., Easton, M. A.

“…This paper presents an overview of a new methodology for investigating the grain refinement performance of alloys and master alloys and then uses this…”
Get full text

Characteristic zirconium-rich coring structures in Mg–Zr alloys by Ma Qian, StJohn, D.H., Frost, M.T.

“…The most characteristic feature of the microstructure of a magnesium alloy that contains more than a few tenths per cent soluble zirconium is the…”
Get full text

The Interdependence Theory: The relationship between grain formation and nucleant selection by StJohn, D.H., Qian, M., Easton, M.A., Cao, P.

“…The Interdependence Theory links grain formation and nucleant selection to improve the ability to reveal the mechanisms of grain refinement, predict as-cast…”
Get full text

Grain Refinement of Magnesium Alloys: A Review of Recent Research, Theoretical Developments, and Their Application by StJohn, D. H., Easton, M. A., Qian, M., Taylor, J. A.

“…This paper builds on the “Grain Refinement of Mg Alloys” published in 2005 and reviews the grain refinement research on Mg alloys that has been undertaken…”
Get full text

Semisolid microstructural evolution of AlSi7Mg alloy during partial remelting by Wang, H, Davidson, C.J, StJohn, D.H

“…Different as-cast microstructures of an AlSi7Mg alloy were produced by controlling the solidification conditions. The as-cast grain size ranged from 1.4 mm to…”
Get full text