Influence of Nickel Particle Reinforcement on Cyclic Fatigue and Final Fracture Behavior of a Magnesium Alloy Composite

Abstract

Abstract:The microstructure, tensile properties, cyclic stress amplitude fatigue response and final fracture behavior of a magnesium alloy, denoted as AZ31, discontinuously reinforced with nano-particulates of aluminum oxide and micron size nickel particles is presented and discussed. The tensile properties, high cycle fatigue and final fracture behavior of the discontinuously reinforced magnesium alloy are compared with the unreinforced counterpart (AZ31). The elastic modulus and yield strength of the dual particle reinforced magnesium alloy is marginally higher than of the unreinforced counterpart. However, the tensile strength of the composite is lower than the monolithic counterpart. The ductility quantified by elongation to failure over 0.5 inch (12.7 mm) gage length of the test specimen showed minimal difference while the reduction in specimen cross-section area of the composite is higher than that of the monolithic counterpart. At the microscopic level, cyclic fatigue fractures of both the composite and the monolithic alloy clearly revealed features indicative of the occurrence of locally ductile and brittle mechanisms. Over the range of maximum stress and at two different load ratios the cyclic fatigue resistance of the magnesium alloy composite is superior to the monolithic counterpart. The mechanisms responsible for improved cyclic fatigue life and resultant fracture behavior of the composite microstructure are highlighted.

Fatigue of Magnesium-Based Materials

“…Carbon nanotubes (CNTs) can be used as reinforcements with magnesium [35] or its alloys such as AZ31, AZ91, ZK60 and AZ61 to improved their ultimate tensile strength, yield strength and modulus of elasticity composite [36]. Different reinforcements such as aluminum oxide particulate Al 2 O 3 [37], nickel particles [38] or nano-size Y 2 O 3 particles [39] have been tested with magnesium and its alloys and found to yield different results.…”

“…Comparison of stress-strain curves of the dual particle reinforced magnesium alloy (AZ31 + Al 2 O 3 + Ni) with the unreinforced matrix alloy (AZ31) cyclically deformed at room temperature (T = 25°C) at R = 0.1 and À 1.0[38].…”