Editing Kirkendall effect (section)

==History==
The Kirkendall effect was discovered by Ernest Kirkendall and Alice Smigelskas in 1947, in the course of Kirkendall's ongoing research into diffusion in [[brass]].<ref name="JOM history">{{cite journal |last=Nakajima |first=Hideo |title=The Discovery and Acceptance of the Kirkendall Effect: The Result of a Short Research Career |journal=JOM |year=1997 |volume=49 |issue=6 |pages=15–19 |url=http://www.tms.org/pubs/journals/jom/9706/nakajima-9706.html |access-date=28 April 2013 |doi=10.1007/bf02914706 |bibcode=1997JOM....49f..15N |s2cid=55941759}}</ref> The paper in which he discovered the famous effect was the third in his series of papers on brass diffusion, the first being his thesis. His second paper revealed that [[zinc]] diffused more quickly than [[copper]] in [[Brass#Types|alpha-brass]], which led to the research producing his revolutionary theory. Until this point, substitutional and ring methods were the dominant ideas for diffusional motion. Kirkendall's experiment produced evidence of a vacancy diffusion mechanism, which is the accepted mechanism to this day. At the time it was submitted, the paper and Kirkendall's ideas were rejected from publication by [[Robert Franklin Mehl]], director of the Metals Research Laboratory at [[Carnegie Institute of Technology]] (now [[Carnegie Mellon University]]). Mehl refused to accept Kirkendall's evidence of this new diffusion mechanism and denied publication for over six months, only relenting after a conference was held and several other researchers confirmed Kirkendall's results.<ref name="JOM history"/>

===Kirkendall's experiment===
A bar of brass (70% Cu, 30% Zn) was used as a core, with [[molybdenum]] wires stretched along its length, and then coated in a layer of pure copper. Molybdenum was chosen as the marker material due to it being very insoluble in brass, eliminating any error due to the markers diffusing themselves. Diffusion was allowed to take place at 785&nbsp;°C over the course of 56 days, with cross-sections being taken at six times throughout the span of the experiment. Over time, it was observed that the wire markers moved closer together as the zinc diffused out of the brass and into the copper. A difference in location of the interface was visible in cross sections of different times. Compositional change of the material from diffusion was confirmed by [[x-ray diffraction]].<ref name="original journal"/>