Deformation twinning in response to cracking in Al: An in situ TEM and molecular dynamics study

In situ tension tests in a transmission electron microscope and molecular dynamics simulations were carried out on pure Al, revealing a localized twinning-responded cracking mechanism. The dynamic twinning at crack tip was suggested to impose dual effects on fracture. On one hand, the intrinsic brittleness of coherent twin boundary (CTB) and the dislocation activities along it could facilitate cracking; on the other, twinning in Al could impede cracking mainly by effectively releasing the concentrated stress at crack tip. The competition between twin growth and CTB brittleness under stress was responsible for the behaving of crack.