Figure 13 shows the impact fracture surfaces of TC4–DT alloy for different heat-treatments. With an increase in heat-treatment temperature and time, the fracture characteristics showed a signifificant difference. From the macro-fractographies, the fracture surface of the sample at 1030 °C/600 s was tearing mode. The micro

fractographies of samples(fifigures 13(d) and (e))were characterized by dimples and small cleavage facets, but the dimples in fifigure 13(d)were deeper and denser. Figure 13(f)shows that the fracture characteristics were composed mainly of shallow dimples, river patterns and large flflat cleavage facets, resulting in a reduction of

toughness.

Figure 13 shows the impact fracture surfaces of TC4–DT alloy for different heat-treatments. With an increase in heat-treatment temperature and time, the fracture characteristics showed a signifificant difference. From the macro-fractographies, the fracture surface of the sample at 1030 °C/600 s was tearing mode. The micro

fractographies of samples(fifigures 13(d) and (e))were characterized by dimples and small cleavage facets, but the dimples in fifigure 13(d)were deeper and denser. Figure 13(f)shows that the fracture characteristics were composed mainly of shallow dimples, river patterns and large flflat cleavage facets, resulting in a reduction of

toughness.