Sk. Hong et al., EFFECTS OF THERMAL RESIDUAL-STRESS ON MECHANICAL-PROPERTIES OF SIC WHISKER-REINFORCED AL-MG AND AL-LI ALLOYS COMPOSITES, Materials transactions, JIM, 37(5), 1996, pp. 975-982
Effects of residual stresses measured by X-ray diffraction on mechanic
al properties in the extruded pure Al, age-hardenable Al-Li, Al-Li-Cu
alloys and solution-hardening Al-Mg alloy matrices composites reinforc
ed with SIC whiskers have been investigated as a function of whisker v
olume fraction and heat treatment process. The tensile residual stress
in the matrix decreased remarkably by liquid nitrogen (L.N.) treatmen
t, and dislocation density in the L.N. treated composite is higher tha
n that in the water-quenched composite. The tensile residual stress in
the matrix decreases the tensile yield strength and increases the com
pressive one, and many dislocations increase also both at the yield st
rengths. Consequently, the tensile yield strength of the L.N.-treated
composites is considerably increased by double positive effects, which
one is due to the reduction of tensile residual stress and the other
is the increase of the average dislocation density in the matrix. Fina
lly, an application of the positive effects of L.N. treatment for the
age hardenable Al-Li-Cu alloy composites leads further increase of the
tensile strength compared to the conventionally aged composites.