Four aluminium alloy powders were extruded in the temperature range 250–550° C and the strain-rate/flow-stress/temperature relationship analysed in terms of exponential functions. The results of ∼400 experimental runs indicate that the powder process is less strain-rate sensitive than is its conventional counterpart. The process is thermally activated and it appears that the rate-controlling mechanism is the climb of edge dislocations or the migration of jogged screw dislocations.
Get full access to this article
View all access options for this article.
References
1.
McGW. J.. Tegart and D. Hardwick, J. Inst. Metals, 1961, 90, 17.
2.
SchoekG., ‘Mechanical behaviour of materials at elevated temperatures’, pp. 79–107. 1961: New York (McGraw Hill).
3.
WongW. A. and JonasJ. J., Trans. Met. Soc. AIME, 1968, 242, 2271.
4.
SheppardT. and ChareP. J. M., Powder Met., 1972, 15, (29), 17.
5.
ChareP. J. M. and SheppardT., ibid., 1973, 16, (32), 437.
6.
BarretC. R. and NixW. D., Acta Met., 1965, 13, 1247.
7.
WeertmanJ., J. Appl. Phys., 1955, 26, 1213.
8.
RaybouldD. and SheppardT., J. Inst. Metals, 1973, 101, 45.
9.
JohnsonW. and KudoH., ‘The Mechanics of Metal Extrusion’. 1962: Manchester (Manchester Univ. Press).
10.
SheppardT. and ChareP. J. M., Int. J. Powder Metall. (to be published).
11.
FelthamP., Metal Treatment, 1956, 23, 440.
12.
SheppardT. and RaybouldD., J. Inst. Metals, 1973, 101, 33.
13.
AnsellG. S. and WeertmanJ., Trans. AIME, 1959, 215, 838.
