An apparatus and method for in-situ bulge testing to understand deformation characterstics like residual stresses, mechanical, and corrosion properties in miniature bulk samples is provided. The same device can also be used to study stress-induced phase transformation in some materials. The apparatus consist of a cap and a holder with two washers between which the miniature bulk sample is held. The use of the washers is optimal and its use depends on the materials to be deformed. The cap further consists of a groove through which the in-situ deformation of samples is studied by irradiation through the groove with an electron beam at different angles. The groove is an additional feature which may be modified depending on the characterization instruments being used. The deformation to the said miniature bulk samples is done with the help of a screw having a head which can take different geometrical shapes and can be torqued manually or automatically. In the present invention mechanical torque is applied to the screw and the deformation of the miniature bulk sample is studied in-situ.