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Procedure of revealing and quantitative description of grain size in as-cast MSR-B alloy

Mateusiak M., Staszewski M., Szala J.

Archives of Foundry Engineering

2007

Vol. 7, iss. 2

75-78

The goal of this paper is to work out a procedure of revealing, as well as qualitative and quantitative evaluation of magnesium as-cast MSR-B alloy microstructure. MSR-B alloy contains additions of silver and rare earth elements. It is characterized by high tensile strength and good creep resistance. These alloys are intended for elements working at higher temperatures (up to 250 oC). Significant stress was put on preparation of metallographic specimens and good conditions of image acquisition for light and scanning microscope. On the basis of testing six etching reagents it was found that the best results from the quality as well as quantity metalography point of view were given by reagent composed of 85% glycol and 15% nitric acid. Analysis of chemical and phase composition of the examinated alloy was performed on samples etched using this reagent. Procedures allowing for significant acceleration and simplification of estimation of quantitative description of [alpha] phase's grains and eutectic precipitation were elaborated.

Structure and mechanical properties of casting MSR-B magnesium alloy

Kiełbus A.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 18, nr 1-2

131--134

Purpose: MSR-B is a high-strength magnesium alloy characterized by good mechanical properties both at an ambient and elevated temperature (up to 200°C). It contains silver and rare earth elements. The aim of this paper is to present the results of research on the microstructure and mechanical properties of the MSR-B magnesium alloy in an as-cast condition. Design/methodology/approach: For the microstructure observation, a Reichert metallographic microscope MeF2 and a HITACHI S-3400N scanning electron microscope with a Thermo Noran EDS equipped with SYSTEM SIX were used. A qualitative phase analysis was performed with a JEOL JDX-7S diffractometer. Quantitative examination was conducted using the “MET-ILO” automatic image analysis programme. Findings: Based on the investigation carried out it was found that the MSR-B alloy in an as-cast condition characterized with a solid solution structure α with island of divorced eutectic (α + (Mg,Ag)12Nd and probably (Mg,Ag)41Nd5 phase). The mean area of the solid solution α grain equals Ā=543 μm2, and the mean surface fraction of eutectic regions is AA= 5.81%. The yield strength is near 90 MPa in 20°C and near 70 MPa in 200°C. Tensile strength is near 180 MPa in both temperatures. The material hardness is 47 HV. Research limitations/implications: Future researches should contain investigations of the influence of alloy additives on microstructure and mechanical properties of MSR_B alloy in as-cast condition and after heat treatment. Practical implications: MSR-B magnesium alloy is used in the aircraft industry, for wheels, engine casings, gear box casings and rotor heads in helicopters. Results of investigation may be useful for preparing casting technology of the Mg-Ag-Nd alloys. Originality/value: The results of the researches make up a basis for the next investigations of magnesium alloys with addition of Ag and Nd designed to exploitation at temperature to 300°C.