Cast irons — effect of alloying additions When elements such as nickel, chromium, copper, and molybdenum are added intentionally to molten cast iron, the product is termed:

Introduction / Context:
Cast irons are iron–carbon–silicon alloys with varied microstructures (grey, white, malleable, nodular). Alloying additions are used to improve specific properties such as high-temperature strength, wear resistance, and corrosion resistance. Correct terminology helps link composition to expected performance and applications.

Given Data / Assumptions:

• Alloying elements include Ni, Cr, Cu, Mo in purposeful amounts.
• Base matrix could be pearlitic, ferritic, or martensitic depending on heat treatment and composition.
• Graphite morphology (flakes, nodules) depends on inoculation and treatment (e.g., Mg for nodular iron).

Concept / Approach:
When cast iron contains deliberate additions of alloying elements to achieve enhanced properties beyond plain grey or white iron, the material is termed “alloy cast iron.” These elements can stabilize carbides (Cr, Mo), enhance toughness and strength (Ni), or improve corrosion resistance (Cu, Ni). The label is independent of graphite form; you can have alloyed grey or alloyed ductile irons depending on treatment.

Step-by-Step Solution:
Identify the presence of alloying elements added for property improvement.Relate additions to targeted properties (wear, heat, corrosion resistance).Apply standard nomenclature: such products are “alloy cast irons.”Therefore select option (d).

Verification / Alternative check:
Standards and handbooks classify irons with significant Ni, Cr, Mo, Cu as alloy cast irons (e.g., Ni-hard, high-Cr irons).

Why Other Options Are Wrong:
White iron refers to carbide-dominated microstructure, not necessarily alloyed. Nodular and malleable describe graphite morphology and heat treatment, not simply the presence of alloying elements. Grey iron only is too restrictive.

Common Pitfalls:
Confusing graphite shape control (via Mg treatment) with alloying; the two are orthogonal levers in cast iron design.

Final Answer:
alloy cast iron