ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The stress induced tetragonal to monoclinic ZrO2 martensitic transformation contribution to fracture toughness is described in terms of the required external strain energy and the thermo-dynamic stability of the constrained tetragonal phase. The strain energy, derived from an externally applied stress acting on the main crack, required to achieve transformation toughening is shown to be a function of the term (T - M s) whereT is the test temperature andM s is the martensite start temperature for the case ofT 〉 M s. Thus for a givenT (T 〉 M s), the transformation toughening component increases asM s approachesT and for a fixedM s, the toughness decreases asT increases. Experimental data for partially stabilized zirconia ceramics confirm these results and show that increasing tetragonal precipitate size is the primary feature which affects an increase inM s. In the case ofT ⩽M s, autotransformation occurs, resulting in decreasing toughness with decrease inT due to a continuous loss in the tetragonal phase content. A temperature region is thus obtained over which transformation toughening exhibits a maximum in its contribution. The temperatures over which this occurs then is shown to be dependent on theM s temperature of the material.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01160553
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